Captain Salisu Mustapha of the special task force in the state said the incident happened late Tuesday in Wadata, a mainly Christian farming village outside the flashpoint city of Jos.
"I can confirm that at least nine people were killed and several injured in the violence between the local farmers and Fulani cattle rearers," he said.
The cause of the latest clashes had yet to be determined, he said.
"We have restored order in the area. The place is now calm but we are still investigating the cause of the fighting," he said.
Residents said up to 20 people might have been killed in the clashes, sparked by the discovery of a local farmer's corpse in the bush.
Plateau state falls in Nigeria's so-called "Middle Belt," where the mainly Christian south meets the majority Muslim north, and has been the site of waves of sectarian and ethnic violence in recent years.
The area has also been attacked by the Islamist group Boko Haram.
