The Ambassador said the attacks have killed at least four people and injured more than 30, but police reported all the dead were Thai citizens.
The attacks came within days of voters having approved a new constitution.
The leader of the country’s military government has suggested the attacks may have been a reaction to voter approval of a referendum entrusting more political power to the military.
Others, he said, suggested that Muslim separatists operating in the south of the country might also have some involvement.
In all, police have said that at least 12 attacks were strung out across seven provinces including the well-known tourist areas of Patong beach, in Phuket, and near a market in Phang Nga, which is famous for its beaches.
The popular beach resort of Hua Hin, about 124 miles south of Bangkok, has been hard hit, with four explosions in total killing at least two people.
Two other deaths have been reported in the southern provinces of Trang and Surat Thani, which tends to attract more-local visitors.