A Frenchman, a German woman and two Argentine women were among the dead, along with three Cubans, Venceremos newspaper said.
It named the dead as 67-year-old Patrick Demer Tesseran, 59-year-old Annegret Frieda Gohike, as well as Roxana Lauseda Gomez and Nadis Carolina Flores, both 35.
In addition to the dead, three Cubans and two foreigners — 42-year-old Spaniard Felicita Hurtado and French woman Marline Alphonse, 63 — were said to be in a serious condition.
“Of the 40 passengers, 22 were foreigners from countries like Holland, England, France, Mexico and Canada,” said Venceremos.
The coach overturned while driving on the road linking the city of Baracoa, near Cuba's eastern tip, to the capital Havana.
The driver said he lost control of the coach due to a wet road, claiming to have been driving slowly, the newspaper reported.
However, it said witnesses said the driver had been attempting to overtake another vehicle when he found himself face to face with oncoming traffic, causing him to swerve off the road.
According to official statistics, there were 11,187 road accidents in 2017 that left 750 people dead and 7,999 injured from a population of 11.1 million.