Police prevented ethnic Serbs from taking over a municipal building in the town of Zvecan where a recently elected ethnic mayor was inaugurated on Friday.
Serbs boycotted the election in April in protest at arrangements between the two communities to cooperate in various areas of mutual interest.
There were also disturbances in three other municipalities in the north.
The tensions have resulted in Kosovo's police and the NATO peacekeeping force, KFOR, having to protect administrative buildings.
Serbian troops on the border with Kosovo were put on high alert on Friday.
