Bui Quoc Thai, director of the Kien Giang Province Department of Tourism, said cable car services, scuba diving and swimming have been stopped.
Provincial authorities have called on travel agencies and hotels to assist their guests.
Phu Quoc, famous for its long sandy beaches and luxury resorts, has entered the peak summer travel season, but May-October is also the rainy season there.
Under the influence of an intertropical convergence zone and a low-pressure area, the country's southwestern coast has been hit by heavy rains, strong winds and rough seas since Sunday.
Phu Quoc received 1.4 million tourists in the first half of this year, or over 70 percent of its full-year target.