The Iranians had sought to seize the Marshall Islands-flagged TRF Moss and hours later the Bahamian-flagged Richmond Voyager, in both cases fleeing after a US destroyer appeared on the scene, the US Central Command said in a statement.

It said that at 1:00 am Wednesday local time, one Iranian naval vessel approached the TRF Moss in the Gulf of Oman.

"The Iranian vessel departed the scene when US Navy guided-missile destroyer USS McFaul arrived on station," the statement said.

Around three hours later, the US Navy received a distress call from the Richmond Voyager, which was positioned more than 20 miles (32 kilometers) off the coast of Muscat, it said.

Another Iranian naval vessel was close to the tanker and messaged it to stop.

Before the arrival of the USS McFaul, "Iranian personnel fired multiple, long bursts from both small arms and crew-served weapons," Central Command said.

Several rounds hit the hull of the tanker but there were no casualties or significant damage, it said.

Central Command said that since 2021 Iran has "harassed, attacked or seized" nearly 20 internationally flagged merchant ships, "presenting a clear threat to regional maritime security and the global economy."