MANAMA, BAHRAIN, SEPT. 23 -- U.S. Navy ships and helicopters combed the waters northeast of here today and reportedly spotted three mines laid by an Iranian naval vessel that was attacked by U.S. forces Monday night.

In Washington, U.S. officials warned American consulates and embassies around the world of possible Iranian-instigated terrorist retaliation in response to the assault.

State Department spokeswoman Phyllis Oakley said, "We've no specific information to indicate that any such acts might occur, but American interests are judged worldwide to be at greater risk" in the wake of the gulf incident, "and we are asking our posts abroad to take appropriate action."

President Reagan, meanwhile, urged Congress not to put any time limit on the commitment of U.S. forces to the gulf. {Details on Page A27}

Three Iranian crewmen were killed and 26 taken into U.S. Navy custody after they fled their burning ship, the Iran Ajr, which was hit by rockets and machine-gun fire by special operations Army helicopters equipped with night vision equipment.

U.S. officials were attempting to arrange the return of the 26, according to State Department and Pentagon officials, who said the plan to fly the sailors from two U.S. Navy ships to Oman for transfer to Iran has hit an unexpected snag.

The problem is that Oman has no Red Crescent organization, the Islamic equivalent of the Red Cross, to supervise the transfer of the sailors.

As a result, U.S. officials are considering asking the Geneva-based International Committee of the Red Cross, or a representative of the Saudi Red Crescent, to travel to Oman to supervise the handover, sources said.

The Iranian crewmen have been shown bound hand and foot to cots on the U.S. flagship LaSalle, guarded by armed American sailors, in television tapes and photos taken by members of a U.S. media pool.

U.S. officials appeared somewhat defensive when asked whether the Iranians were being treated in a "humane" fashion, as the administration asserted yesterday.

"Well, they weren't beaten," one official said. "Think about how the Iranians treated our hostages" from the American Embassy in Tehran in 1979-81.

Meanwhile, merchant shipping in the Persian Gulf was warned to stay clear of the area where the Iranian mines were dropped, and the mine-hunting operation appeared to complicate the departure from Kuwait of the 10th U.S.-escorted mission that is expected to accompany the reflagged Kuwaiti vessel Gas Prince through the area.

U.S. Secretary of Defense Caspar W. Weinberger said in a television interview today that American forces have found three mines and expect to find three more planted by the crew of the Iran Ajr.

"The Iranian crew have been somewhat helpful in telling us where they are," he said before leaving Washington for the Persian Gulf region.

In Tehran, Iranian leaders met in a Cabinet session and afterward called on the nation to prepare itself to confront the American "conspiracy" against Iran in the wake of the attack on the Iran Ajr.

Tehran radio said, "The Cabinet deplored the attack and said it was carried out despite efforts by Iran to ease the tension in the Persian Gulf region."

The statement added that Iranian leaders emphasized "the need for the Iranian nation to be ready to confront the U.S. conspiracy."

At the same time, the general staff of Iran's Revolutionary Guards put out a call for 2 million new vol"The Cabinet deplored the attack and said it was carried out despite efforts by Iran to ease the tension in the Persian Gulf region."

-- Tehran radio

unteers to sustain Iran's war effort. Speaking after the Cabinet meeting, Minister of Islamic Guidance Mohammed Khatami said Iran had been through difficult stages in the seven-year-old gulf war.

"Undoubtedly, this crucial stage will lead to an eventual victory and will bring further humiliation to the United States," he said, according to Tehran radio.

On the Arab side of the gulf, there was still little reaction to the U.S. military strike on the Iranian mine-laying vessel as shipping industry officials told ship captains to take additional precautions, such as steaming closer to Arab coastlines, to avoid retaliatory attacks from Iran.

Reports from the southern end of the gulf said there was an unusual amount of Iranian naval activity late today, and that a number of merchant vessels were being challenged and interrogated by Iranian forces to determine their cargo and destination.

U.S. Navy officials, meanwhile, were preparing for Weinberger's five-day visit to the region. He is expected to meet with Arab leaders in Saudi Arabia and Bahrain, two nations that reportedly have supplied sensitive support to U.S. military operations in the region.

Weinberger declined to discuss any details of the trip other than to note that he will also visit several naval vessels of the 30-ship U.S. task force in the area to ask military personnel their "reaction and their views."

Iraq continued its air war against Iranian economic targets today, bombing a power station, sugar plant and cement factory in Bakhtaran, according to a communique issued in Baghdad.

Earlier, Iran's news agency said Iranian gunners mounted a 24-hour artillery barrage against Iraq's southern city of Basra and nearby Zubair in retaliation for Tuesday's Iraqi air raid, which Iranian officials said killed 21 civilians and wounded 196.

Iraq's news agency said 12 civilians, including a woman and two children, were killed in the shelling attack last night and today.

Iranian military officials also said they shelled the Umm Qasr naval base at the mouth of the Shatt al Arab waterway. Iraq claimed to have sunk two Iranian boats in the same area last night.

Washington Post staff writers Molly Moore and David B. Ottaway contributed to this report in Washington.