The NATO-led peacekeeping mission in Kosovo (KFOR) stands ready to intervene if needed, Secretary-General Jens Stoltenberg told Serbian President Alexandar Vucic on Wednesday.
The two had a phone call in which they discussed "tensions in northern Kosovo," Stoltenberg said on Twitter.
He called on all sides to "engage constructively in the EU-mediated dialogue, and solve the differences through diplomacy."
"The KFOR stands ready to intervene if stability is jeopardized, based on its UN-mandate," Stoltenberg added.
On Tuesday, Stoltenberg had a call with Albania's Prime Minister Albin Kurti, and conveyed a similar message.
Tensions rose on Sunday ahead of a new Kosovar law supposed to take effect on Aug. 1, making it mandatory for everyone, including Serbs living in Kosovo, to have a Kosovo ID card and license plate.
Kosovo has now postponed for a month the implementation of the new border rules.
Kosovo declared its independence from Serbia in 2008, with most UN member-states, including the US, UK, France, Germany, and Türkiye, recognizing it as an autonomous country.
The KFOR international peacekeeping mission has been operating in Kosovo since 1999.
Following the border tensions, the EU's diplomatic service invited on Monday both sides to hold talks in Brussels in order to solve the dispute and prevent new ones.
Launched in 2011, the EU-led Belgrade-Pristina Dialogue aims to normalize relations between the two Balkan countries and to find a mutually agreeable solution for the disputes in the framework of a legally binding agreement.
