Warning comes just weeks after Iran detained 10 US sailors after their boats entered its territorial waters
Iran's navy on Wednesday warned a US warship to leave an area of the Sea of Oman where the Iranians were holding an exercise, the Tasnim news agency said.
The agency, close to the Revolutionary Guards, reported that after the warning to the vessel, it left the area instantly and "the situation returned to normal".
Iran detained 10 US sailors on Jan. 12 after their boats entered its territorial waters because of what they said was a navigational error.
They were quickly freed, bringing a swift end to an incident that had rattled nerves just before the expected implementation of a landmark accord between Iran and world powers.
A few days later, international sanctions on Tehran were rolled back in return for its curtailment of some nuclear activities.
Iran said its naval drill near the strategic Strait of Hormuz on Wednesday was to test submarines, destroyers and missile launchers.
"The manoeuvre aims to show Iranian forces' strength both in ensuring security on the seas and in defending the country's sea borders in Hormuz Strait, Sea of Oman and north of the Indian Ocean," Rear-Admiral Habibollah Sayyari was quoted as saying by state news agency IRNA on Wednesday.
Tasnim news agency reported on Wednesday that Iran had given warnings to other Western ships on Tuesday, and they had cleared the area.