The attack comes just two weeks after fighting between Christian militias and Muslim gunmen based in the area killed 21.
The spokesman for the Seleka, Ahmt Nadjad, a Muslim rebel coalition that overthrew the government in 2013, said the Christian anti-Balaka militia attacked the village of Ardo-Djobi early today, killing 18 of the local Fulani tribal population. One militiaman also died.
Ibrahim Saleh, a resident of Bambari, confirmed the figures.
Christian militias have since sought revenge for atrocities committed during Seleka rule. The sectarian violence has left thousands dead and forced nearly 1 million people to flee their homes.