President Reagan's order sending U.S. military aircraft into a dramatic interception of the Egyptian airliner carrying four Palestinian terrorists yesterday "should send a message and a strong one" that the United States is prepared to use military force against terrorism, presidential spokesman Larry Speakes said last night.

"If the opportunity presents itself we will do exactly this again," he said of the administration's first successful deployment of military force against terrorists, one that redeemed Reagan's five-year-old vow of "swift and effective retribution" against terrorism.

But even as the White House was declaring the operation to be a signal of future resolve, the incident threatened serious damage to America's relationship with one of its most valuable Arab allies, Egypt. Speakes said last night that despite U.S. displeasure with Cairo in allowing the terrorists to flee, the administration "wants to emphasize the fundamental and durable interests that the United States and Egypt share, interests which transcend this difficult incident. These have been trying times for both our governments."

"We will do all we can to insure that [the] basic U.S.-Egyptian relationship in which both our countries have taken so much pride for so long remains unaffected," he added.

In a late night news conference, Speakes said Reagan was "deeply disturbed" to learn earlier yesterday that Egypt might allow the four Palestinians who killed an American on the Italian cruise ship Achille Lauro to escape prosecution. He said Reagan advised Egyptian President Hosni Mubarak strongly against allowing such an escape.

Speakes said he could "categorically deny that there was any deal" with Egypt that permitted the U.S. interception of the pirates.

Mubarak apparently ignored Reagan's demand earlier in the day that the hijackers be restrained and extradited. Reagan, while returning to Washington at 3:20 p.m. EDT yesterday on Air Force One from Chicago, approved a plan for Navy F14 fighters from the carrier Saratoga to intercept the Egyptian plane once it left Egyptian airspace. Earlier, Reagan had told aides he was prepared to order military force if needed to apprehend the hijackers.

Asked if Mubarak had misled the United States when he said early yesterday that the terrorists had already left Egypt, Speakes avoided making any accusation against the Egyptian president. "I don't think we can be absolutely certain about our facts," the spokesman said.

Speakes announced last night that the United States would seek "prompt extradition to the United States of those involved in the crime . . . on the grounds that an American citizen was murdered and American citizens were terrorized."

The interception of the Egyptian plane brought a host of ironies. A day that began with Reagan and his aides angry and frustrated over a lack of information about the location of the hijackers ended with exultations that they had been captured. Speakes said the U.S. operation was "carefully thought out, carefully planned, carefully coordinated."

Defense Secretary Caspar W. Weinberger said last night the interception "has many of the fine features we believe were exemplified in the Grenada operation," the 1983 U.S. invasion and rescue mission at that Caribbean island.

Another irony was praise for Tunisia, where the headquarters of the Palestine Liberation Organization was bombed by Israel last week. Reagan had suggested that the bombing was justified, irritating Tunisia and other Arab states. Last night, Speakes said Tunisia had refused permission for the Egyptian airliner to land in Tunis. He expressed gratitude to the government of President Habib Bourguiba.

Speakes also expressed "our gratitude to the government of Egypt for its efforts to end this dangerous crisis without additional loss of life. We strongly disagreed with the government of Egypt, however, on disposition of the terrorists."

Word that the hijackers had been captured brought bipartisan rejoicing on Capitol Hill last night. "Thank God we've won one," said Sen. Daniel Patrick Moynihan (D-N.Y.).

Senate Majority Leader Robert J. Dole (R-Kan.) said, "An American was killed. We had a direct interest in the case . . . . We want to commend those who were involved" in the apprehension.

Even before the Egyptian plane had been intercepted, Reagan expressed frustration about the terrorist attack but indicated that the administration was primed to use force. At a Chicago high school yesterday afternoon, Reagan said the United States was "ready and prepared" to take action against the hijackers who terrorized hundreds of passengers on the Italian ship.

Administration officials confirmed that Delta Force, the Army's secret commando team, had been sent to the Mediterranean early in the crisis to prepare for a possible rescue, but that the passengers and crew were released before it could be carried out.

White House officials were openly worried and confused throughout yesterday, acknowledging that they had little information on the whereabouts of the four Palestinian terrorists. The officials feared a repeat of last summer's Lebanon hostage crisis, in which a Navy diver was killed but the hijackers of TWA Flight 847 were not apprehended.

"This terrorism and this thing that is going on in the world is the most frustrating thing to deal with," Reagan said in Chicago yesterday. "You want to say retaliate when this is done, get even. But then what do you say when you find out that you're not quite sure that a retaliation would hit the people who were responsible for the terror and you might be killing innocent people?

"So you swallow your gorge and don't do it."

Reagan said the United States did not plan to retaliate now for the hijacking. "No, we're going to try and do this in a legal manner," he said. "The time for action, which could have been taken by us, is passed and was ended when the rescue was made."

Reagan, who came into office promising "swift and effective retribution" for terrorism, has been widely criticized in recent years for the administration's failure to respond with military force to acts of terrorism in the Middle East and Central America.

The question of when and how to retaliate has been one of the most intensely fought internal debates of Reagan's presidency, pitting the military, which has urged caution, against the State Department and Secretary George P. Shultz, who has argued for the use of military force.

Reagan has said he would approve such retaliation only if the actual terrorists could be identified and if innocent lives would be spared. Speakes last night said that U.S. pilots intercepting the Egyptian airliner were operating under specific "rules of engagement" but he refused to comment on whether they would have fired against it. Speakes did note, however, that the plane was intercepted "without firing of shots."

During the hijacking of the Achille Lauro, the U.S. Army's antiterrorist Delta Force was flown to a forward base, believed to be in Sicily, to stage a rescue operation if the hijackers did not surrender, officials said.

The Navy's antiterrorist Seal teams were not in position to attempt a rescue, sources said, so the mission fell to the Army and its Delta Force. But the Seal teams apparently were well-positioned to surround the Egyptian plane when it was forced to land in Sicily last night.

As events unfolded yesterday, the relatives and friends of the American hostages aboard the Achille Lauro suffered further frustration as they waited to be reunited with their loved ones and for retribution against the pirates who killed 69-year-old Leon Klinghoffer of New York.

"What kind of a deal can you make with people who are so inhuman that they could murder a cripple," Carol Hodes, a longtime friend of the Klinghoffer family, said in a telephone interview. "I want these people brought to justice."

In New York, the Klinghoffers spent the day in their apartment, turning away visitors, including two rabbis who had wanted to offer their condolences.

The families' frustration was echoed at the White House during the day, as officials expressed fear that Mubarak would allow the hostages to flee. A senior White House official, flying with Reagan on Air Force One back to Washington, said "we are disappointed" that Egypt, a close U.S. ally, had not apprehended the hijackers. Only hours before the Egyptian plane left Cairo, officials said they had no idea where the hijackers were.

Reagan administration officials said the United States had joined Italy in a bid for extradition of the hijackers from Egypt. The Palestinian terrorists were promised safe passage by Egypt in return for leaving the ship, apparently before Cairo discovered they had killed Klinghoffer, a retired merchant from New York.

The State Department's legal adviser, former federal judge Abraham Soafer, who presided in the libel case that former Israeli defense minister Ariel Sharon brought against Time magazine, was drawing up papers last night to be filed with Italian courts today requesting extradition to the United States from Italy.

A senior U.S. official said Egypt made the deal to free the hijackers with the concurrence of Italy, Britain and Switzerland, but not the United States.

Italian sources said yesterday that the ambassadors of the United States, West Germany, Italy and Britain had met with Egyptian Foreign Minister Esmat Abdel Meguid, who had presented them with the free-passage deal. The ambassadors had approved it in principle if there were no casualties on the ship, the sources said, and were still discussing it when news came of Klinghoffer's murder.

"No final and official decision had been taken," one official said.

The crisis dominated Reagan's day as he traveled to Chicago to push his tax overhaul plan. He said the pirates should be turned over "to a sovereign state" for trial and punishment.

Asked whether he believed that Mubarak was lying when he said the pirates had been turned over to the PLO, Reagan replied, "The case is whether he has all the same information or the information he should have, too. Earlier, in his work to get the hostages freed, he did not know that a crime had been committed."