Iran tested more missiles in the Arabian Gulf on Thursday, state media said, while the United States pledged to defend its allies against any Iranian aggression.
Washington, which fears Tehran wants to master technology to build nuclear weapons, said after Iran test fired nine missiles on Wednesday that Tehran should halt further missile tests if it wanted to gain the world's trust.
Iran said the missiles could hit Israeli and U.S. bases.
Speculation that Israel could bomb Iran has mounted since a big Israeli air drill last month. U.S. leaders have not ruled out military options if diplomacy fails to end the nuclear row.
Iran has responded by saying it will strike back at Tel Aviv, as well as U.S. interests and shipping, if it is hit. Tehran insists its nuclear program has only civilian goals.
U.S. Secretary of State Condoleezza Rice said on a visit to the former Soviet republic of Georgia that Washington was sending a message to Iran that it would defend American interests and those of its allies.
"We take very, very strongly our obligation to help our allies defend themselves and no one should be confused about that," Rice said after meeting Georgian President Mikheil Saakashvili.
Wednesday's tests rattled global oil markets, pushing up the price of oil.
Iranian state TV and radio said the new missile tests took place during the night into Thursday.
"Deep in the Persian Gulf waters, the launch of different types of ground-to-sea, surface-to-surface, sea-to-air and the powerful launch of the Hout missile successfully took place," state radio said without giving further details of the missiles.
Iranian satellite channel Press TV said Hout was a torpedo.
The reports followed remarks on Wednesday night by Guards air force commander Hossein Salami, who had told state television that a "night missile maneuver" was taking place. But he gave no details at the time.
Press TV said the new missile tests were part of an ongoing military maneuver.