The Pentagon on Friday acknowledged that the crew of the USS Vincennes made several mistakes in shooting down an Iranian airliner but concluded that the ship's captain, based on what he had been told, "did what his nation expected of him."

The chairman of the Joint Chiefs of Staff, Adm. William Crowe, said that an investigation of the July 3 tragedy found that Capt. Will C. Rogers III and his crew were acting under severe stress as the airliner approached them during a surface engagement with Iranian gunboats.The Vincennes mistook the airliner for an F-14 fighter and shot it down, killing 290 people.

"The commanding officer never received the clear evidence that he thought he needed to establish that the Iranian aircraft had not come to participate in the ongoing surface action," Crowe told a news conference.

Defense Secretary Frank C. Carlucci told reporters he had decided to withdraw a letter of censure proposed for one of the ship's officers, despite mistakes made by that officer.

Crowe said that President Reagan had received the report and concurred with its findings.

Crowe cited these mistakes:

-A conclusion that the civilian Airbus was descending rather than ascending as it approached the Vincennes.

-A report that the jetliner was transmitting a signal identifying it as a military aircraft.

-A report by Crowe on the day of the incident that the plane was outside a commercial air corridor crossing the Persian Gulf.

Crowe said that, taken individually, the mistakes "were not crucial to the decision" to fire two Standard missiles at the Airbus.

"Even cumulatively, they do not change the picture in a decisive way," said Crowe.

"Our past expereicne in the gulf, the intelligence available to the ship, and the rules of engagement all supported such a judgment" by the ship's captain, Crowe said.

"I believe that giving the operating environment, Capt. Rogers acted reasonably and did what his nation expected of him in defense of his ship and crew," Crowe said.

"The main recommendation of the investigation was that no disciplinary should be taken against any U.S. naval personnel associated with this incident," said Crowe.

Despite some shifts, the findings of the final report were largely consistent with the Pentagon statements on July 3 in emphasizing the stressful combat environment in which Rogers and his crew operated.

The report offered a wealth of new detail: the officers in the command and control center could hear gunfire from the surface battle outside, including the noise of bullets pinging off the metal hull; the ship was heeling at a 32-degree angle as the airliner approached, making it difficult for the men to stand, causing objects to fall off flat surfaces and lights to flicker.

"I dare say that it would be hard to even have this press conference under those conditions, much less reach critical decisions on a number of targets during a very short time-frame," said Carlucci.

In all, Carlucci said, Rogers faced a series of problems "he could not control or discount" in the seven minutes between the plane's departure from an Iranian field and the destruction of the Airbus.

Crowe laid much of the blame for the tragedy on Iran.

"An examination of the events on 3 July leads quickly to the conclusion that Iran must share responsibility for the tragedy, and the investigation so found."