U.S. Secretary of State Condoleezza Rice warned Tehran in an interview published Tuesday that it should cease its "provocations" after Iranian vessels confronted U.S. warships in the Gulf.
"Iran should not engage in such provocations," Rice said in an interview with the Jerusalem Post and the Ynet Web site in Israel after Washington said armed Iranian speedboats had threatened three U.S. warships in the Strait of Hormuz.
"That's what it was and it needs to stop. The U.S. is going to defend its interests. It's going to defend its allies," Rice was quoted as saying.
Iran is "the single greatest threat to the kind of Middle East we all want to see," she added.
The weekend incident, in which the Iranian boats radioed a threat to blow up the U.S. ships, U.S. officials said, sent tensions rising ahead of the President George W. Bush's visit to the region.
"It was provocative, and that kind of provocation is dangerous," Rice also told the BBC's Arabic service. "I would sincerely hope that the Iranians would refrain from any such activity."
The Strait of Hormuz is a crucial energy supply route, with about 20-25% of the world's crude oil passing through from Gulf oil producers.
The U.S. Fifth Fleet is based in Bahrain and US Navy officials say about three dozen U.S. and coalition warships are in the region at any one time. The aircraft carrier USS Harry Truman currently is in the Gulf.
"The United States under this president has sent a very strong signal that America has strong interests in the Gulf, that the United States will continue to defend its interests in the Gulf, and this goes back for decades," Rice told the BBC.