Iran's Islamic Revolutionary Guards Corps blasted a mock-up US aircraft carrier with missiles on Tuesday during exercises in Gulf waters, state television reported.
The operation – designated "Prophet Mohammed 14th" – took place near the Strait of Hormuz, a vital shipping lane for a fifth of global oil output.
The US Navy said the "irresponsible and reckless behaviour by Iran" was an attempt "to intimidate and coerce".
The Iranian maritime manoeuvre was staged at a time of heightened tensions between Iran and its arch enemy the US.
Footage of the war games broadcast on state television showed the Guards Corps' air and naval forces preparing for an attack off the southwestern coast.
Speedboats skimmed formation before ground forces fired cannon, and a missile was launched from a helicopter.
The mock-up of a Nimitz class aircraft carrier came into view with rows of dummy fighter jets on either side of its deck.
The television then cut to rockets being fired out to sea from trucks, before showing damage to the hull of the target.
Another missile fired from a helicopter left a trail of smoke before appearing to smash into the side of the giant vessel.
Airborne troops were then seen rappelling onto the deck, before a dozen speedboats began circling.
"What was shown today in these exercises, at the level of aerospace and naval forces, was all offensive," Guards commander Major General Hossein Salami told state television.
New long-range missiles were fired during the exercises, a spokesman said.
"Some surprise equipment and weapons were used, such as long-range ballistic missiles capable of striking offensive floating targets in the distance," General Abbas Nilforoushan said, quoted by the Guards' Sepahnews website.
The US Navy 5th Fleet, which is based in Bahrain, criticised Iran's use of the fake aircraft carrier, which first appeared on Monday in satellite images.
"We are aware of the Iranian exercise involving attacking a mock-up of a vessel similar to a motionless aircraft carrier," spokeswoman Commander Rebecca Rebarich said on Tuesday.
"The US Navy conducts defensive exercises with our partners promoting maritime security in support of freedom of navigation; whereas, Iran conducts offensive exercises, attempting to intimidate and coerce.
"While we are always watchful of this type of irresponsible and reckless behaviour by Iran in the vicinity of busy international waterways, this exercise has not disrupted coalition operations in the area nor had any impact on the free flow of commerce in the Strait of Hormuz and surrounding waters."
She earlier said that the US "remains confident in our naval forces' ability to defend themselves against any maritime threat.
"We do not seek conflict but remain ready to defend US forces and interests from maritime threats in the region."
The war games came days after Tehran accused US Air Force jets of harassing an Iranian commercial airliner over Syria.
At least four passengers on board the Mahan Air plane were injured in Thursday's incident, after the pilot took emergency action to avoid the warplanes, Iranian authorities said.
Tensions have escalated between Tehran and Washington since President Donald Trump unilaterally withdrew the US from the landmark 2015 Iran nuclear deal with six world powers in 2018.
The arch foes have come to the brink of direct confrontation twice since June 2019, when the Guards shot down a US drone in the Gulf.
Their animosity deepened after Iran's most prominent general, Qassem Suleimani, was killed in a US drone strike near Baghdad airport in January.
One of the most recent confrontations was in mid-April, when the US accused the Guards of using speedboats to harass its warships in the Gulf.
