Kosovo's government late Sunday postponed for a month the implementation of new border rules that sparked tensions in the north of the country where ethnic Serbs blocked roads and unknown gunmen fired on police.

Police closed two border crossings with Serbia on Sunday after the incident during which no one was injured, a police statement said.

Kosovo proclaimed independence from Serbia in 2008 but ethnic Serbs who make up the majority in the northern region do not recognise Pristina's authority.

They remain politically loyal to Serbia which still provides financial support.

The latest tensions came after Pristina said from Monday, people entering Kosovo with Serbian IDs will have to replace them with a temporary document during their stay in the country.

The government also said ethnic Serbs who have vehicle registration plates issued by Serbia would have to change them for Kosovo licence plates within two months.

Prime Minister Albin Kurti said on Sunday it was a reciprocal move since Belgrade requires the same from Kosovo citizens entering Serbia.

But, after meeting with US ambassador to Kosovo Jeffrey Hovenier, who told reporters he sought from Pristina that implementation of the new regime be postponed for 30 days, the government pledged to do so.

The government said in a statement it would postpone the implementation of the two decisions until September 1, seeking that "all barricades are removed and full freedom of movement is established" on Monday.

EU foreign policy chief Josep Borrell on Twitter hailed Pristina's decision and said he expected "all roadblocks to be removed immediately".

On Sunday evening, hundreds of ethnic Serbs parked trucks, tankers and other heavy transport vehicles on roads towards the Jarinje and Brnjak crossings with Serbia, blocking traffic, an AFP correspondent said.

Large crowds of local Serbs gathered around the barricades with the intention to remain there.

"The atmosphere has been brought to a boil," Serbian President Aleksandar Vucic said earlier Sunday, warning that "Serbia will win" if Serbs are attacked.

Kurti accused Vucic of igniting "unrest".

NATO-led peacekeepers from the KFOR mission in a statement labelled the security situation in Kosovo's north as tense.

The last major tensions in the region were in September when hundreds of ethnic Serbs staged daily protests and blocked the traffic at the two border crossings.

Their anger was triggered by Pristina's decision to require drivers with Serbian registration plates to put on temporary ones when entering Kosovo.

Those entering from Kosovo had to do the same in Serbia.

EU-led talks between Kosovo and Serbia launched in 2011 have so far failed to achieve any normalisation of ties.

Kosovo is already recognised by about 100 states, including the United States and most EU countries, but Serbia refuses to do so.