The bus, operated by a company running onshore excursions, was carrying 12 passengers, including 10 cruise ship guests, at the time of the collision.
The majority of those injured had been discharged from a local hospital, the spokeswoman said.
The passengers were travelling on the cruise ship Azura, which departed from Southampton on 28 October for a 14-night trip.
More than 3,000 guests and almost 1,200 crew are onboard. The passengers involved in the incident had not been named and representatives of P&O Cruises were at the hospital to support those injured.
Paul Ludlow, the senior vice-president of P&O Cruises, said: “Our thoughts and prayers go out to everyone touched by this tragic event.
“Our employees and crew are working to do everything we can to extend support and assistance to those affected and their loved ones.”
P&O Cruises said it was working closely with local authorities and the safety and wellbeing of guests and crew was its “absolute priority”.