Serb ultranationalists gathered in Belgrade to protest at a festival that was promoting Kosovan-Albanian culture.
It comes just a day after Serbia put its troops on high alert following the arrest of 19 people in an anti-crime operation in restive northern Kosovo, in an area primarily populated by ethnic Serbs.
The aim of the festival is to close the rift between Serbian and Albanian communities through film, debate, and exhibition.
Beginning in 2014, the festival is dubbed “Miredita, dobar dan,” or “good day".
"The festival is sending a clear message... that barriers and obstacles must be removed instead of creating new ones," said organisers.
Riot police cordoned off the festival, which was being held in a cultural centre in downtown Belgrade. The protestors chanted “Kosovo is Serbia” and "We will not give up Kosovo" and clashed briefly with the police.
Tensions between Serb and Albanian communities have persisted in the Balkans since the end of a war in the late 1990s.
In 2008, Kosovo, which was formerly a southern province of Serbia, declared independence. Belgrade does not recognise this declaration.
Many Serbs view Kosovo as the heart of their nation, culture, and Christian Orthodox faith.
Serbia, which was granted EU candidate status in 2012, is still seeking to join the bloc. To do so, many believe the nation must reign in their ultranationalistic stances.
On Monday, President of Serbia Aleksandar Vucic told his parliament that Serbia must accept that it has lost Kosovo.
The festival is set to last until Saturday and is organised by Belgrade's Youth Initiative for Human Rights.