IRGC gunmen fired on the tanker north-east of Oman, the UK Maritime Trade Operations Center (UKMTO) said in an online statement, adding that the ship and crew were safe.
Vanguard identified the tanker as the India-flagged tanker Sanmar Herald.
It quoted the captain as saying that two IRGC patrol boats approached him without any radio contact and “opened fire, resulting in damage to the bridge windows”.
Separately, Vanguard said the Malta-flagged cruise ship Pisces Schiff 4 reported a splash nearby while transiting the strait from Iran to Oman.
“The master confirmed VHF (radio) traffic from IRGC units saying, ‘We are conducting operations, we will open fire and destroy you,’ but there were no casualties,” Vanguard said.
In a third incident, UKMTO said it received reports of a container ship “hit by an unknown projectile” in the same area, causing damage to some containers but no fire.