The conflict between the countries in the Balkans is not new.
Serbia does not recognize Kosovo, which declared independence in 2008.
The unrest has recently flared up again, after the Kosovo government decided last summer that all cars in the country should have Kosovo Albanian license plates - something that around 50,000 Kosovo Serbs refuse.
On Wednesday, Kosovar authorities announced that the main border crossing with neighboring Serbia has been closed due to the unrest.
Arrested policeman released
For barely a month, Kosovo Serbs in northern Kosovo have set up roadblocks on roads and in towns.
The protesters are demanding the release of a Serbian police officer who was arrested.
He was arrested earlier in December on suspicion of trying to destroy polling stations and attacking police officers in Kosovo with Albanian roots.
At lunchtime on Wednesday, the court in the Kosovar capital Pristina announced that the arrested policeman should be released from custody and instead put him under house arrest, reports Reuters.
Accusing Russia
Earlier this week, the conflict further escalated when Serbian President Aleksandar Vucic ordered the highest alert on the border with Kosovo.
Kosovo's Interior Minister Xhelai Svecla has accused Serbia of destabilizing Kosovo with the support of Russia.
Serbia, for its part, denies the accusations, and says it wants to protect the Serbian minority in the country.
Russia has also denied the accusations, but has expressed its support for Serbia.
According to Serbian Defense Minister Milos Vucevic, Serbian President Aleksandar Vucic is in talks with the US, Great Britain, France, Italy and Germany about how the unrest between Kosovo and Serbia can be resolved.