Foreign ministers from สล็อต the Group of Seven wealthy economies said Iran was threatening international peace and security and that all available evidence showed it was behind an attack on the Mercer Street tanker last week.
"All available evidence clearly points to Iran. There is no justification for this attack," said the statement, issued by current G7 chair, Britain.
The vessel was a Liberian-flagged, Japanese-owned petroleum product tanker managed by Israeli-owned Zodiac Maritime.
Tehran has denied any involvement in the suspected drone attack in which two crew members - a Briton and a Romanian - were killed.
In a separate statement, the US military said explosives experts from the Ronald Reagan aircraft carrier - which deployed to assist the Mercer Street - concluded the drone was produced in Iran.
It said the explosives experts were able to recover several pieces of a drone, including a part of the wing and internal components which it said were nearly identical to previously-collected samples of Iranian attack drones.
The US military also suggested the attack may have been launched from the Iranian coast, saying the distance to the locations of the attacks "was within the range of documented Iranian one-way attack" drones.