An Israeli-owned ship preparing to depart for Haifa from the Greek port of Syros in the Aegean Sea was searched by a bomb disposal team following a bomb threat, according to Greek newspaper Kathimerini.
The Panama-flagged cruise ship, Crown Iris, is operated by Mano Shipping, and had 940 passengers and 597 crew members on board, according to information obtained by Kathimerini.
Some reports indicated that passengers were evacuated as a precautionary measure.
According to reports in the Greek media, the warning was received directly by the captain via radio transmission, claiming that an explosive device was placed on the ship's hull beneath the waterline.
The Coast Guard's Underwater Missions Unit is expected to conduct a second, more thorough inspection after an initial search by the Port Authority found no suspicious objects.
The bomb threat came after local authorities banned a left-wing protest against the docking of the cruise ship at the Syros port.
Pro-Palestinian activists have repeatedly protested at Greek ports where the cruise ship has docked in recent years, including in Syros itself.
Yoav Etiel contributed to this report.