US forces hit Iranian rocket launchers near the Strait of Hormuz on Sunday, a US official said, marking the first US military action against Iran in a month.
Iran's Islamic Revolutionary Guard Corps was preparing to launch rockets carrying sea mines into the strait when US forces struck, the official said.
Iranian media reported explosions near Larak Island, while the IRGC said several fighters and civilians had been killed or wounded.
In a statement carried by Iran's state broadcaster, it noted “the martyrdom and injury of several of our fighters and compatriots", without giving an exact toll.
The statement said the attack would “result in punishment of the aggressor".
The strike came days after the administration of US President Donald Trump said it would focus on increasing economic pressure on Tehran rather than military action.
Mr Trump said last week that mines had been cleared from international shipping lanes in the Strait of Hormuz and warned Iran that any vessel trying to lay new mines would be destroyed.
The last known US strikes on Iran took place in late July. Fighting has since largely stalled, with Washington shifting its focus towards economic pressure and threatening to impose sanctions on countries that continue to do business with Tehran.
The US and Israel launched attacks on Iran on February 28, prompting Tehran to retaliate against Israel and the Gulf states hosting US military bases. The conflict has now passed the six-month mark.
Thousands of people have been killed and millions displaced by US and Israeli strikes on Iran and by Israeli attacks in Lebanon. Eighteen US service members have also been killed.
The war has disrupted shipping through the Strait of Hormuz, a critical energy route that before the conflict carried about a fifth of the world's oil supply.
