Four Serbs and two K-For soldiers have been injured in a clash in northern Kosovo during an attempt by peacekeepers to clear roadblocks.
The Nato-led force said its soldiers had fired rubber bullets and tear gas after Serbs threw stones at a roadblock near the town of Zvecan.
The soldiers were shot, reportedly hit by pistol fire from the crowd.
Serbs set up roadblocks last year after Kosovo and the EU tried to take control of the disputed border with Serbia.
The border has been the scene of recurrent violence between K-For and ethnic Serbs who make up the majority in northern Kosovo.
Serbia's new nationalist President, Tomislav Nikolic, was sworn in on Thursday.
Earlier this week, Mr Nikolic said he would "never" recognise Kosovo as an independent state, even if it meant sacrificing the chance of EU membership.
The K-For action to remove barricades is being seen by some Serb analysts as a warning to the new Serbian president to respect EU-mediated agreements reached by his predecessor, Boris Tadic, earlier this year, the BBC's Nick Thorpe reports.