Kosovar authorities have deported a senior Serbian government official who had traveled to the north of the country, defying a ban by Pristina.
Kosovar special police units detained the head of the Serbian government’s office for Kosovo, Marko Djuric, in the ethnically divided town of Mitrovica on March 26.
Officers also fired tear gas to disperse a crowd of ethnic Serbs protesting against the arrest.
Djuric was transferred to a court in Pristina, before being expelled from the country.
Police earlier said they had sent reinforcements to northern Kosovo to stop Djuric and other Serbian officials from entering the country.
The incident added to already high tensions between Kosovo and Serbia.
Serbian President Aleksandar Vucic said the Kosovar police's use of force and the detention of Djuric amounted to a "brutal provocation” and a “criminal act."
"We will not let this go unpunished," Vucic said in an address aired live on Serbian media.
However, he also called on Serbs in northern Kosovo to remain calm and stopped short of pulling out of European Union-mediated talks on normalizing ties with Kosovo.
Kosovo's President Hashim Thaci also called for calm, saying the incident “should not violate the communication between Kosovo and Serbia."
EU foreign policy chief Federica Mogherini wrote on Twitter, “Djuric now free on his way back. Need calm & preserve dialogue."
The U.S. ambassador to Pristina, Greg Delawie, expressed concern over the incident and said there was “no alternative” to dialogue between Belgrade and Pristina.
Kosovo’s Albanian majority declared independence from Serbia in 2008, but Belgrade has refused to recognize the former province's statehood despite its recognition by 116 other countries.
EU-brokered normalization talks have stalled in spite of a framework deal signed in 2013.
Tensions remain high, both between Belgrade and Pristina and between Kosovo's dominant majority ethnic Albanian population and its minority Serbs.
It was not clear how Djuric and another official from Serbia -- the Serbian Presidency’s Secretary-General Nikola Selakovic -- entered North Mitrovica, where the two attended a roundtable discussion on how to strengthen "Serbian institutions" in Kosovo.
"For Serbia, Kosovo and Metohija, the north of Kosovo and Metohija, is not and will never be part of the so-called independent Kosovo or part of the so-called Greater Albania," Djuric told the gathering.
"Just as we did not give up today, despite all the threats, bans, cordons, and controls, just as they did not manage to stop us, as we did not give up, we will not give up our fight for a search for a solution that does not destroy or humiliate Serbs and Serbia," Selakovic said.
To visit Kosovo, Serb officials must first seek official clearance from Kosovo's authorities.
Earlier, Kosovar Foreign Minister Behgjet Pacolli told a press conference that Djuric was not allowed to enter the country because of recent statements which he said "fomented hatred."
"We have asked him to respect the rules and submit the request 72 hours before the visit. Therefore, he cannot enter Kosovo today," Pacolli said.
The minister later wrote on Facebook that "anyone who enters Kosovo illegally will be arrested."
A day of EU-brokered negotiations between the leaders of Kosovo and Serbia broke up late on March 23 without any reported progress on efforts to normalize relations.
Vucic did not appear at a news conference immediately after the meeting but later on Serbian TV Pink accused Kosovo of stalling the implementation of a 2013 agreement on special rights for municipalities with a majority Serb population.
Thaci stressed the urgency for the two countries to reach an agreement on normalization this year.
Mogherini in a statement stressed that a comprehensive normalization agreement between two countries is a key condition for both countries to further their bids to join the EU.
The EU is pushing for completion of the normalization agreement by the end of 2019.