TEHRAN — Iran accused America today of fabricating video and audio released by the Pentagon showing Iranian boats confronting American warships in the Persian Gulf.

The video from Sunday’s incident shows small Iranian boats swarming around American warships in the Strait of Hormuz. In the recording, a man speaking in heavily accented English threatened, “I am coming to you. … You will explode after … minutes.”

“The footage released by the U.S. Navy was compiled using file pictures and the audio has been fabricated,” an official in Iran’s Revolutionary Guards was quoted as saying by the state-run English-language channel Press TV.

State TV did not give the name of the Revolutionary Guard official and did not offer more details about how the official knew the footage was “fabricated.”

A Defense Department spokesman, Bryan Whitman, said the “allegation is absurd, factually incorrect, and reflects the lack of seriousness with which they take this serious incident.”

The national security adviser, Stephen Hadley, warned Iran against more confrontations.

“This is a provocative act — not a smart thing to do, and they are going to have to take responsibility for the consequences, if they do it again,” Mr. Hadley told reporters aboard Air Force One as President Bush flew from Washington to Israel.

He added that his comments should not be seen as a threat.

Mr. Whitman said it was “fortunate that we did not have to escalate to the use of force, but as always, we are prepared to if our vessels are threatened in international waters.”

In the four-minute, 20-second video released yesterday, the Iranian boats appeared to ignore repeated warnings from the American ships, including horn blasts and radio transmissions. The video was shot from the bridge of the destroyer USS Hopper.

After spotting the approaching Iranian boats, a Navy crew member on the Hopper says over the radio: “This is coalition warship. I am engaged in transit passage in accordance with international law. Intend no harm.”

The audio and video recordings were made separately but were pulled together by the Navy. Often uneven and shaky, the video condenses what Navy officials have said was a confrontation of about 20 minutes.

The Iranian fleet of high-speed boats charged the American warships and threatened to blow up the Navy convoy as it passed near but outside Iranian waters, according to the top Navy commander in the Gulf, Vice Admiral Kevin Cosgriff. The Iranian fleet “maneuvered aggressively” and fled as the American ship commanders were preparing to open fire, he said. No shots were fired.

Iran’s Revolutionary Guards has said that its high-speed boats never threatened the American vessels during the encounter, insisting it only asked them to identify themselves, then let them continue into the Gulf.

Defense Minister Mostafa Mohammad Najjar called Western news reports that the boats threatened to blow up the American warships “mischief.”

“(Iranian) navy units … asked them to identify themselves. They responded accordingly and continued their path,” the official IRNA news agency quoted Mr. Najjar as saying.

He said the encounter was normal.

“The identification of vessels passing through the Strait of Hormuz by Iranian navy units is a natural occurrence,” IRNA quoted Mr. Najjar as saying. “Islamic Republic of Iran navy units always put questions to passing vessels and warships at the Strait of Hormuz and they need to identify themselves. This is in accordance with the normal procedures.”

Admiral Cosgriff, the commander of U.S. 5th Fleet, which patrols the Gulf and is based in nearby Bahrain, said the American vessels, which were clearly marked, had been identified by Iranian authorities earlier in the day.

The confrontation was an unusual flare-up of American-Iranian tensions in the Persian Gulf as Mr. Bush prepared for his eight-day Middle East trip, designed in part to counter Iran’s influence in the region. Mr. Bush, who arrived in Israel today, is expected to discuss the America stance toward Iran with Arab allies that are also worried about Tehran’s desire for greater regional power.

Many Arab countries fear the Iranian-American rivalry could erupt into a military confrontation that would put them in the crossfire and hurt vital oil traffic through the Strait of Hormuz.