An American navy vessel fired a warning shot towards an armed Iranian fishing vessel during a brief encounter in the volatile Persian Gulf, said the US Coast Guard.
The confrontation occurred when the US ship was on a routine patrol and officials insisted that the incident did not spiral out of control.
The US Coast Guard patrol boat Monomoy dispatched an inflatable boat to make contact with the Iranian dhow, a traditional vessel in the Middle East. Nonetheless, the Iranian boat is said to have stopped communication abruptly.
"The dhow's crew trained and prepared to fire a .50 caliber machine gun on their small boat as it approached as part of a routine maritime security operation," said the US navy.
"This action by the dhow's crew demonstrated hostile intent, which resulted in the defensive fire by the Coast Guardsmen."
The US officials say the incident took place at about 11:30 am local time in international territorial waters and the American forces acted in self defence.
The Iranians are yet to respond regarding the incident.
It is still unclear whether the Iranian-flagged ship belongs to the Islamic Revolutionary Guard Corps. The Iranian navy have used such strategies to transport arms from Iran to Yemen and other places.
Vessels from the US and Iran have been involved in such tense confrontations in the last decade in the Strait of Hormuz and the Persian Gulf.