KUWAIT, OCT. 19 -- Iran today accused the United States of launching a "full-scale war" in the Persian Gulf and vowed to avenge the American attack on its oil platform "with a crushing blow."

Iran's chief of war information, Kamal Kharrazi, said in a statement issued by the state news agency, "The United States has entered a swamp from which it can in no way get out safely."

Later, President Ali Khamenei, speaking on state radio after a meeting of the Supreme Defense Council, said Iran would "take decisive retaliatory action," and he warned that "{President} Reagan, by this action, has made a big mistake."

Arab leaders on the other side of the Persian Gulf praised the U.S. military action in private, but distanced themselves in public from any cooperation with the U.S. forces that might draw a retaliatory blow from Iran.

In Abu Dhabi, a presidential official said: "We think it is another positive step. We think it is a message, and it has been shown that messages are received {by Iran}."

In Kuwait, whose territory and oil-transport lifeline has been most threatened by Iranian attacks, there was official silence over the U.S. action. One Kuwaiti official, asked whether the government would comment, said, "Why would there be any comment? This does not concern Kuwait in any way."

Some western sources in the region said they feared Iran might take revenge against Arab oil platforms in the lower gulf as it did last November after Iraq launched its first long-range bombing raids against Iranian oil platforms and terminals in the vicinity of today's U.S. naval attack on an Iranian platform.

The official in Abu Dhabi said U.S. retaliation for Iran's Silkworm missile attack on the U.S.-flagged Kuwaiti tanker Sea Isle City, which blinded the American captain and injured 17 other crewmen, had been "expected," but will not succeed without a coherent U.S. policy to help end the seven-year-old war.

"It's too dangerous to have mere escalation if it is not backed by any kind of policy," the official said.

This official said that military escalation involving the United States would likely be "exploited" by the Soviet Union, which he said must participate in any diplomatic solution pursued by the United Nations.

The Soviets today denounced the U.S. attack.

"The confrontation is a fact now," said Tass commentator Mikhail Krutikhin in Moscow. "What is obvious is that the latest military adventurism will not bring political dividends to the American administration."

In this increasingly threatened emirate and in Saudi Arabia, Bahrain and the United Arab Emirates, Arab defense officials were said by sources to be seeking U.S. and western assistance to beef up their air defense forces. Their concerns were raised by the alarming accuracy with which Iran fired two Silkworm missiles from the Faw Peninsula at the head of the gulf, hitting U.S.-owned or registered oil tankers in Kuwait's oil-loading port last week.

Brig. Gen. Jed Pearson of the U.S. Central Command has just completed consultations with defense officials here on possible redeployments and improvements to Kuwait's arsenal of U.S.-made Hawk antiaircraft missiles.

U.S. officials believe the Hawks, if operated correctly, can shoot down the Chinese-made Silkworms, which fly at relatively slow speeds and at low altitudes.

One western official said new Kuwaiti antimissile training and improved tactics will soon "make it harder" for an Iranian Silkworm to penetrate Kuwait's airspace successfully.

Kuwait unsuccessfully fired Soviet-made SA7 missiles at the two Silkworm missiles last week, according to western sources.

Bahrain was also said by western officials to be pressing the United States to sell advanced shoulder-fired Stinger antiaircraft missiles to defend the island emirate from Iranian air or missile attacks.

Bahrain's rulers were said to be angered by reports that Iran has acquired U.S.-made Stingers while U.S. officials continue to resist Bahrain's requests to purchase the missiles and while Bahrain openly provides U.S. naval forces with basing facilities in the central gulf.

Sources strongly indicated today that the key factors in the selection of the Iranian oil platform as the target of an American response for Silkworm missile were:A desire by the United States to avoid sending its warplanes into the front-line battle areas of the Iran-Iraq war, where Iran is believed to have set up several batteries of Silkworm missile sites near the tip of the Faw Peninsula to threaten Kuwait-bound shipping.The inability of the United States to project its airpower easily from aircraft carrier decks 600 miles south of the Iranian sites.A reluctance by Kuwaiti officials to request U.S. retaliation for missile attacks that occurred in their territorial waters, because such an overt joining of defense interests might further embroil Kuwait in the war.

One senior western official cited "obvious technical and logistical" problems with sending U.S. warplanes on a round trip the length of the gulf, which would require overflights of Oman and the United Arab Emirates that those countries have told American officials they would not permit, Arab sources said.

In addition, U.S. forces would have to fly refueling tankers out of Saudi Arabian air bases, thus involving that country directly in a raid.

The western official said that "one of the reasons" that made today's American attack a "measured response" was that it was targeted "at an oil platform out in international waters."

"One thing that is a factor," this official continued, "is that what you want to do is not do anything that would further enmesh Kuwait or any other state in the war" or that possibly would give the Iranians "any legitimate case for some action against Kuwait."

"You don't always target where people think you will," the official said. "You target where you can conveniently go and make your point and hope they get the point -- and that doesn't mean you can't go further."

Oil industry officials said that while U.S. military forces sought to punish Iran for using Rostam, the oil facility hit today, as a base for harassing merchant shipping in the gulf, the loss of that platform would have an insignificant impact on Iran's oil production.

Developed in 1966, the Rostam field was producing only 18,000 barrels a day of crude oil a decade later, and for the past two years production all but ceased due to damage done by Iraqi bombing raids.

"That platform was a wreck when I was out there two years ago," said one gulf shipping official. "That's really a soft target, but the Americans are doing what they want to do, and maybe they made their point."

This official said he was concerned that Iran might retaliate against vulnerable oil platforms in the heavily populated offshore oil industry of the lower gulf between Qatar and the Emirates.

Iranian F4 Phantoms bombed Abu Dhabi's Abu Bakoosh and Fatah offshore fields late last year, killing four French oilfield workers and setting ablaze an oil tanker in the Emirates' territorial waters. The bombing raid, never acknowleged by Iran, was taken as a warning to Arab leaders to pressure Iraq to stop bombing Iran's oil installations in the lower gulf.

But one Emirates official said today that new batteries of antiaircraft missiles have been deployed on many of the offshore platforms and should act as a deterrent to Iranian retaliation.

In the wake of the U.S. attack, Kuwaiti and Saudi officials appeared to be mobilizing their military forces in a public display of resolve and in anticipation of Iranian retaliation.

Kuwait announced that its Air Force would conduct live bombing exercises against naval targets near Kubbar Island, about 25 miles off its main oil loading terminal at Ahmadi.

Reports from Saudi Arabia said a half-dozen Saudi and Kuwaiti helicopter gunships were deployed to the Dhahran air base to be available in case of Iranian attacks against the Saudi and Kuwaiti offshore oil fields.

The American-made Cobra gunships were backed up by a U.S. electronic intelligence aircraft and by three U.S. P3 Orions that are used for maritime surveillance, the reports said.