"The attack took place around 1:00 am (0000 GMT) and 13 people were killed in their sleep" in Rapyem village, said Habila Dung, administrator of the Barkin Ladi local government area in Plateau state.
He described the raid as "barbaric" and said nine children were among the dead.
Plateau falls in Nigeria's so-called Middle Belt, on the dividing line between the mainly Christian south and predominantly Muslim north.
Fulani leaders say the Berom politicians who control the state have systemically suppressed the rights of herdsmen, denying them access to desperately needed grazing land.
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It was not clear who carried out the latest attack in Barkin Ladi, a hotspot in the protracted conflict.
Police spokeswoman Felicia Anslem said it was an isolated incident and that calm had been restored, adding that police were working to verify the casualty figure.
The US-based Council on Foreign Relations, which tracks unrest in central Nigeria, says that between May 29, 2011 and January 31, 2012 there were 1,131 deaths in Plateau related to social, economic or religious grievances.
Several peace processes have failed to stop the violence, with deep mistrust persisting between the state's politicians and the security forces.
Berom leaders have accused the military of supporting and at times cooperating with the Fulani but such allegations have not been proven.