The elite Iranian Revolutionary Guard Corps, staging a mysterious military exercise, issued a warning that Israel and U.S. naval forces in the Persian Gulf would be targets if Iran is attacked.

The Web site of the Iranian force posted a statement late Monday announcing the military drill, which it said involved "missile squads," but did not say where it was taking place. Iran's guards and national army hold regular exercises two or three times a year, but the statement did not say whether this drill was one of them or if it was a special exercise.

The exercises came as the U.S. Navy, in cooperation with the U.K., wrapped up a 6-day exercise in the Persian Gulf called Stake Net.

U.S. Navy officials told FOX News that they believe the Revolutionary Guards were conducting their exercises in response to recent U.S. Naval activity. Navy officials said they will monitor the Iranian exercises but at this point had no details on what the operations looked like.

In January, Revolutionary Guard boats approached a U.S. warship in the Strait of Hormuz in what the Pentagon described as a "provocative act."

Israel's military sent warplanes over the eastern Mediterranean for a large military exercise in June that U.S. officials described as a possible rehearsal for a strike on Iran's nuclear facilities, which the West fears are aimed at producing atomic weapons.

The Iranian Web Site quoted guard official Ali Shirazi as saying that Israel's coastal metropolis of Tel Aviv and U.S. warships in the Gulf would be among the first targets if Iran comes under attack.

"The Zionist regime is pushing the White House to prepare for a military strike on Iran," Shirazi was quoted as saying. "If such a stupidity is done by them, Tel Aviv and the U.S. naval fleet in the Persian Gulf will be the first targets which will be set on fire in Iran's crushing response."

Shirazi is a cleric who represents supreme leader Ayatollah Ali Khamenei in the guards' naval force. Khamenei has the final say over all state matters.

"The first shot by the U.S. on Iran will set the U.S. vital interests in the world" at risk, Shirazi said, according to the Web site.

The U.S. Navy's Fifth Fleet, headquartered in the Persian Gulf nation of Bahrain, is responsible for patrolling the Gulf, the Suez Canal and parts of the Indian Ocean.

Israeli government spokesman Mark Regev would not comment on Shirazi's warning other than to say "his words speak for themselves."

Though Washington says it prefers a diplomatic resolution to the standoff over Iran's nuclear activity, the U.S. and Israel have not ruled out a military option. Iran insists its nuclear program is only for peaceful purposes, such as energy production.

On Friday, Iran's top Revolutionary Guards commander, Gen. Mohammed Ali Jafari, said Iran would consider any military action against its nuclear facilities as the beginning of a war.

However, Iranian leaders have said they believe the speculation of a military strike is part of a campaign of psychological warfare.

The five permanent members of the U.N. Security Council — the United States, Britain, France, China and Russia — as well as Germany have offered new talks if Iran signals it is prepared to suspend its enrichment of uranium, a possible pathway to developing weapons.

FOX News' Justin Fishel and the Associated Press contributed to this report.