In addition to the tourists, the Cuban driver and tour guide were also hurt, said the news agency Prensa Latina.
Seven of the French nationals were in serious condition after the accident in central Cuba following a visit to a monument to Che Guevara, said an official at the French Embassy.
All 43 injured were taken to a hospital in Cienfuegos, 250 kilometers (160 miles) southeast of Havana, the diplomat said.
The bus struck a vehicle traveling in the same direction as the bus was returning to Varadero from Santa Clara, where the tourists had visited a monument that holds the remains of the Argentine-Cuban guerrilla fighter.
Cuban television said the bus was dragged several meters and locals used a crane to lift the bus and help the injured, it reported.
The accident came during the busy season for Cuban tourism, in which thousands of visitors from Europe, Canada and Latin America flock to the island.
Tourism is one of Cuba's main source of revenue. The government has forecast it will receive around three million visitors this year.