The US has accused Iran of trying to shoot down a US drone to prevent surveillance during suspected attacks on oil tankers in the Gulf of Oman.
A US Central Command spokesman said Iranian Revolutionary Guard troops had fired a modified surface-to-air missile to try to bring down a drone that had been observing the Front Altair and Kokuka Courageous tankers.
The international community has blamed Iran for attacks on the tankers, with the US military claiming that video footage shows Iranian Revolutionary Guard troops removing an unexploded mine from the Kokuka Courageous.
Crew members from the Norwegian-owned Front Altair landed in Dubai on Saturday after two days in Iran.
The other tanker is now anchored off the coast of the United Arab Emirates.
Iran has rejected allegations, accusing the US of pursuing an "Iranophobic" campaign against it.
Tensions have been rising between the US and Iran - Donald Trump withdrew America from the 2015 nuclear deal that Iran reached with world powers and recently imposed a series of sanctions.
Iran’s leaders have repeatedly threatened to close the vital Strait of Hormuz, through which 20% of the world's oil flows.
Four other oil tankers off Fujairah have suffered similar attacks in recent weeks, and Iranian-allied rebels from Yemen have hit US ally Saudi Arabia with drones and missiles.