Iranian ships recently taunted two U.S. Navy vessels as part of escalating tensions in and around the Persian Gulf's Strait of Hormuz.
The incidents in the strait, one of the world's most important oil routes, occurred last week and involved the USS New Orleans, an amphibious transport dock, and the Coast Guard Cutter Adak, the military said Friday in releasing videos of the incidents.
Iranian speed boats are seen in one of the videos approaching the USS New Orleans within about 500 yards last Friday.
"The Iranian boats did not respond to whistle signal or voice queries from the New Orleans, disregarding standard maritime protocols," Central Command said in releasing the videos. In the incident involving the Adak, "communications were established with a larger Iranian ship operating in the area and the speed boats ceased their harassment."
One senior defense official told FoxNews.com that the Iranians "intended to be harassing" but it didn't go much beyond that. No shots were fired.
Iran, which recently held war games in the area, has threatened to block the Strait of Hormuz if provoked, and it has warned U.S. Navy ships to steer clear.
The rising tensions coincide with increased pressure on Iran over its nuclear program, which the West fears is merely a front for Iran's clandestine work on developing nuclear weapons.
Diplomats said Thursday that a senior U.N. nuclear agency team will visit Tehran on Jan. 28, with Iran saying it is ready after years of refusal to discuss allegations that it was involved in secret nuclear weapons work.
Diplomats have previously said that International Atomic Energy Agency officials were discussing such a trip with their Iranian counterparts. But before the diplomats' comments Thursday, no date -- or indication that Iran was ready to talk about the allegations -- had been mentioned.
Any follow-through on the part of Iran on its reported pledge to discuss nuclear arms suspicions would be significant.
For more than three years, Tehran has blocked IAEA attempts to follow up on U.S. and other intelligence alleging covert Iranian work on nuclear arms, dismissing the charges as baseless and insisting all its nuclear activities were peaceful and under IAEA purview.
Faced with Iranian stonewalling, the IAEA summarized its body of information in November, in a 13-page document drawing on 1,000 pages of intelligence. It stated then for the first time that some of the alleged experiments can have no other purpose than developing nuclear weapons.
Iran continues to deny the charges and no change in its position is expected during the Tehran talks with IAEA officials. But even a decision to enter a discussion over the allegations would be a major departure from outright refusal to talk about them -- and create hopes of future progress in the investigation.
Two diplomats told The Associated Press that Iranian officials had suggested they were ready to talk about the issue during recent meetings with officials of the Vienna-based IAEA. They asked for anonymity because their information was confidential.
Iran denies it is trying to make nuclear weapons, saying its program is for peaceful purposes only and is geared toward generating electricity.
Those claims were called into question on Monday when the IAEA confirmed Iran had begun increasing its production of uranium enriched to 20 percent. That's a significantly higher concentration than the nation's main stockpile -- and can be turned into weapons-grade material more quickly than the lower enriched uranium.
Fox News' Jennifer Griffin and Justin Fishel and the Associated Press contributed to this report.