French Sports minister Amelie Oudea-Castera says Novak Djokovic’s political message about Kosovo was “not appropriate” and has warned the Serbian superstar he should not repeat it.

Speaking on TV station France 2, Ms Oudea-Castera said French Open director Amelie Mauresmo spoke with Djokovic and his entourage to insist on the principle of “neutrality” on the field of play.

“When it comes to defending human rights and bringing people together around universal values, a sportsperson is free to do so,” she said.

But Ms Oudea-Castera added that Djokovic’s message was “militant, very political” and “must not be repeated”.

Djokovic has drawn criticism from Kosovo’s tennis federation after offering his thoughts on clashes in northern Kosovo between ethnic Serbs and police and NATO peacekeepers.

After a French Open first-round victory in Paris on Monday, Djokovic wrote in Serbian on the lens of a courtside TV camera: “Kosovo is the heart of Serbia. Stop the violence.”

Tweet from @kosovar_kras

Kosovo’s tennis federation said Tuesday that Djokovic’s comments were “deplorable” because he was stoking tensions between Serbia and Kosovo.

A former province of Serbia, Kosovo’s 2008 declaration of independence is not recognised by Belgrade.

Ethnic Albanians make up most of the population, but Kosovo has a restive Serb minority in the north of the country bordering Serbia.

Djokovic, who has won 22 grand slam titles, was scheduled to play in the second round at Roland Garros on Wednesday.

Speaking in Serbian on Monday, Djokovic said he thought what he wrote on the TV camera was “the least I could do. I feel responsibility as a public figure … as well as a son of a man who was born in Kosovo.”

Without mentioning Djokovic by name, French Open organisers indicated in a statement issued Tuesday that no rules had been broken, saying: “Occasionally, discussions about international news events enter the realm of the tournament, which is understandable.”