Nearly 6,000 sailors remain stranded in the Persian Gulf region, warned the Secretary-General of the International Maritime Organization (IMO), Arsenio Dominguez, quoted by "Agence France-Presse".
He called for "maximum restraint and de-escalation".
"I condemn the attacks over the past two days against several ships transiting the Strait of Hormuz", Dominguez stressed in an official statement after US President Donald Trump announced that the truce with Iran was over.
"These reckless attacks have once again exposed innocent sailors to serious danger", Dominguez pointed out.
At the NATO summit in Turkey, Trump announced that negotiations with Iran were over and sharply criticized the Iranian leadership, stating: "In my opinion, it's over. I don't want to deal with them. They're scum. Sick people. They're run by sick people".
Hours earlier, Iran announced that it had carried out missile and drone strikes against American targets in Bahrain and Kuwait in response to Washington's renewed strikes on Tehran. The American bombings were provoked by new Iranian attacks on ships in the Strait of Hormuz.
Kuwait sounded its air raid sirens and condemned the attacks as a violation of its sovereignty.