Louis Cruises said two passengers died when the Louis Majesty was struck by "abnormal waves" while sailing in the Mediterranean on Wednesday.
Louis Cruises identified the passengers only as a German and an Italian national. Another 14 passengers suffered minor injuries.
"Louis Cruises regrets to announce that its ... Louis Majesty while sailing from Barcelona to Genoa [Italy] was hit by abnormal waves," the cruise line said. "As a result, the windows in a public area on Deck 5 on the forward part of the vessel smashed, resulting to the fatal injury of two passengers."
According to an Associated Press report, Greek and Cypriot officials said the ship was hit by 26-foot waves.
The 40,876-gross-ton ship, the former Norwegian Majesty, was carrying 1,350 passengers and 580 crew. The ship was headed back to Barcelona following the incident.
The ship was on a 12-day cruise and was due to return to Genoa on March 4.