The injured included two Britons, eight Chinese and two Japanese, all of whom suffered burn injuries, Mohamed Shareef, the government spokesman, said.
Maldives police did not immediately know how the bomb was detonated or where it was planted, Shareef said.
"The Maldives has never had something like this before. We are taking this very seriously because tourism is our life blood," Shareef said.
"They (the tourists) are still in a state of shock, and police have still not interviewed them," Shareef said.
Concern
He said it was too early to say whether the bomb targeted the tourism industry, adding that all possibilities would be investigated.
Some Western diplomats have expressed concern about the potential for violence in this Sunni Muslim country.
Half the population is under 18, reasonably well-educated and with few prospects for good jobs. Some young people have turned to drug use, while others have embraced a conservative strain of Islam that had been virtually unheard of on the islands just a few years ago.
Attacks against the tourist trade are virtually unheard of, though there has been tension and occasional outbreaks of violence in recent years between opposition activists and government forces, who are controlled by President Maumoon Abdul Gayoom, who has ruled the country with an iron fist for 29 years.
Authorities will seek help from Interpol, the United States and India in investigating the blast, Shareef said.
The opposition Minivan News reported on its Web site that witnesses said they saw nails, presumably from the bomb, scattered in the park, which is located near the country's army headquarters.
The Maldives, with a population of about 350,000, is by far the wealthiest, and most orderly, country in south Asia.
About 600,000 tourists visit the country each year, accounting for one-third of its economy.