Iran's Foreign Ministry says an explosion caused minor damage to an Iranian cargo vessel in the Red Sea.
Ministry spokesperson Saeed Khatibzadeh said on Wednesday the blast occurred on Tuesday morning near the Djibouti coast.
He said the incident is under investigation.
The ministry said the ship in question was deployed in the Red Sea to provide protection against piracy.
Meanwhile, The New York Times on Tuesday quoted the U.S. Naval Institute as saying the vessel is a covert military ship operated by Iran's Revolutionary Guards.
It also quoted a US official as saying that Israel informed the United States it carried out the attack on the vessel.
The explosion coincided with indirect talks held by Tehran and Washington in Vienna on Tuesday aimed at finding ways to revive the 2015 nuclear deal reached between Iran and world powers.
Former US President Donald Trump unilaterally pulled out of the accord in 2018.
Israel opposes the pact.