Reagan administration officials yesterday expressed disappointment and unhappiness at Italy's decision to allow a Palestinian leader apprehended with the four hijackers of the cruise ship Achille Lauro to depart for Yugoslavia. The State Department last night asked the Yugoslav government to detain Mohammed Abbas until the United States can request his extradition.

There was no immediate indication of how Yugoslavia will respond to the U.S. request.

Overall, the officials said that the administration does not want the dispute with Italy to injure U.S.-Italian relations. That was the initial, private response of U.S. officials to the apparent decision by Prime Minister Bettino Craxi's government to ignore a U.S. arrest warrant charging Abbas with "masterminding" the abortive ship piracy and allowing him and another Palestinian to leave Italy on a Yugoslav airliner destined for Belgrade.

The initial White House reaction to the Italian decision was a vow to "vigorously pursue" those responsible for the hijacking but to issue no public criticism of Italy. Later, the State Department issued a lengthy declaration that concluded:

"The U.S. government remains appreciative of Rome's larger cooperation in the Achille Lauro incident. While we are deeply disappointed at Italy's decision to release Abbas, we recognize that we have a very broad and deep relationship with this valued NATO ally. That relationship will continue."

Abbas heads a faction of the Palestine Liberation Front that is closely allied with Palestine Liberation Organization Chairman Yasser Arafat. He was one of six Palestinians aboard an Egyptian plane intercepted by U.S. Navy jets and forced to land in Sicily on Thursday. He was not on the Achille Lauro when four Palestinians hijacked it on Monday and killed an American passenger before surrendering early Thursday to Egyptian authorities.

The Justice Department announced yesterday that it had obtained an arrest warrant from U.S. District Court Judge Charles Richey here Friday, and it was relayed immediately to Rome in an effort to persuade the Italian government to keep Abbas in custody.

The warrant charged him with hostage-taking, piracy and conspiracy to commit both offenses, and a Justice Department spokesman said:

"We believe he masterminded the ship hijacking and controlled the operation from a nearby location. He planned it, the whole business."

The State Department's declaration said Abbas was "one of the most notorious Palestinian terrorists and has been involved in savage attacks on civilians."

But, it added, the Italian government had replied that its judicial authorities did not consider the evidence offered by the United States strong enough to warrant Abbas' further detention.

The U.S. government apparently was not surprised at Abbas' release. One administration official said the White House was aware Friday night that the Craxi government probably would let Abbas go to preserve its close ties with the PLO.

The official said the administration pursued the warrant in hopes of persuading the Italian government to change its mind but that it had little hope the attempt would succeed.

"The Italians have good relations with the PLO and Arab countries, including Libya, and they want to maintain them. They want to have it both ways," the official added.

FBI Director William H. Webster, speaking earlier yesterday before Abbas was released, told reporters after a meeting of the Business Council in Hot Springs, Va., that "two crack FBI teams" have arrived in Italy to help Italian authorities prepare the prosecution of the four Palestinians that Italy has said it will prosecute for the Achille Lauro hijacking.

"We're going to work closely with them to be sure they have all the evidence we can develop, all the intelligence we can develop, and we will have access to their information to further build our criminal cases," Webster said.

That was a reference to tentative U.S. plans to ask for extradition of the four so they can also be tried in this country. "Whether we ultimately prosecute them because the Italians do their job and it would be unnecessary duplication, remains to be seen. We don't know the answer to that yet," Webster added.

The Justice Department said last night that it had obtained arrest warrants for the four hijackers and had forwarded them to the Italian government to prepare the way for a possible U.S. extradition request.

The administration's desire not to get into a fight with Italy paralleled its attempts to prevent the forcing down of the Egyptian jetliner from damaging its relations with Egyptian President Hosni Mubarak, America's principal ally in the Arab world.

Mubarak has been embarrassed badly by the apprehension of the plane leaving Egyptian territory after he had said publicly that the hijackers already were out of his country.

Egypt also had complained that Abbas and the sixth Palestinian, whose identity is still unclear, were mediators who had helped to convince the hijackers to surrender without harming other passengers or crew members on the Achille Lauro. Accordingly, Egypt had demanded that they be returned to Cairo.

President Reagan's national security affairs adviser, Robert C. McFarlane, who also addressed the Business Council in Hot Springs, sought to take a conciliatory approach in talking with reporters about the U.S. differences with Egypt. "We had a disagreement. But we can pick up relations," he said.

Asked whether the Egyptians had exercised their sovereignty legitimately in releasing the hijackers, McFarlane replied:

"That implies that a sovereign has no responsibility to act against terrorists. They made a mistake but we can repair it . . . We can pick up the pieces . . . "

Webster added that the United States has indications Egypt might seek U.S. cooperation for its investigation into the hijacking. He said, "It's a very positive sign that our relations are getting back to normal . . . . "