"Kosovo is the heart of Serbia. Stop the violence," 22-time Grand Slam champion Djokovic wrote on a camera lens in Serbian.
Some 30 NATO peacekeeping soldiers defending three town halls in northern Kosovo were injured in clashes with Serbs protesters in the town of Zvecan, where Djokovic's father grew up. Serbian authorities said 52 protesters were injured in clashes.
The tense situation developed after ethnic Albanian mayors took office in northern Kosovo's Serb-majority area after elections the Serbs boycotted - a move that led the U.S. and its allies to rebuke Pristina on Friday.
"As a son of a man born in Kosovo, I feel the need to give my support to our people and to entire Serbia," Djokovic told a news briefing on Monday after his match at the Roland Garros tournament.
"My stance is clear: I am against wars, violence and any kind of conflict, as I’ve always stated publicly. I empathise with all people, but the situation with Kosovo is a precedent in international law," Djokovic said.
The French tennis federation (FFT), which organises the event, told Reuters that there were "no official Grand Slam rules on what players can or cannot say. The FFT will not be making any statement or taking any stance on this matter."
"Kosovo is our cradle, our stronghold, centre of the most important things for our country... There are many reasons why I wrote that on the camera," RFI radio quoted Djokovic as saying to Serbian media.
Djokovic will hope to avoid another political distraction at a Grand Slam after he defended his father at the Australian Open in January, when a video emerged showing him posing with some fans holding Russian flags amid the war in Ukraine.
Ethnic Albanians make up more than 90% of the population in Kosovo as a whole, but northern Serbs have long demanded the implementation of an EU-brokered 2013 deal for the creation of an association of autonomous municipalities in their area.
Serbia and its traditional ally Russia do not recognise Kosovo's independence, and Moscow has blocked the country's bid to become a member of the United Nations.
Djokovic beat Aleksander Kovacevic (24) 6-3, 6-2, 7-6 on Monday in the first round.
