Iran on Saturday rejected as psychological warfare accusations that it was behind a deadly attack on a tanker off Oman's coast, and said Tehran sought to enhance the security of the strategic Gulf waterway.

Foreign ministers from the Group of Seven wealthy economies said on Friday Iran was threatening international peace and security and that all available evidence showed it was behind the attack on the Mercer Street tanker last week.

"If we were to confront enemies... we would declare it openly, so the recent storytelling by the enemies is a psychological operation," state media quoted Abolfazl Shekarchi, Iran's senior armed forces spokesman, as saying.