No injuries were reported in the incident at around 6:00 am (0400 GMT) as armed transporters approached to remove a truck in the centre of the Kosovo Serbs' barricade, an AFP correspondent reported.
Some 150 Serbs tried to prevent Kosovo peacekeeping (KFOR) soldiers from dismantling the roadblock near the Brnjak crossing into Serbia, but dispersed after the tear gas was released.
The situation afterwards was calm but tense, as Serbs set on the road in order to stop further KFOR's action.
Earlier, two convoys of at least 100 armed transport vehicles, trucks and dredges of the Kosovo peacekeeping forces (KFOR) moved towards the Brnjak border crossing into Serbia.
The convoys stopped a few hundred meters (yards) before the roadblocks on the two roads leading to the Brnjak crossing as a few hundred local Serbs swiftly gathered at each of the barricades.
There has been a tense stand-off between KFOR troops and Kosovo Serbs over two roadblocks barring access to the Brnjak and Jarinje and crossing points.
The NATO move came after talks with Serb leaders in northern Kosovo on Wednesday had failed to produce a deal over the barricades which block access to the sensitive border crossings between Serbia and its breakaway republic Kosovo.
Following the new development Serbian President Boris Tadic urged both sides to remain calm, Tanjug reported.
"I demand KFOR and EULEX (the EU mission in Kosovo) to restrain from the use of force," Tadic told the agency, adding that local Serb "citizens must not undertake violent reactions at any price."
Around 40,000 Serbs live in northern Kosovo, making up the majority in a number of towns. They refuse to recognise the authority of the ethnic Albanian government in Pristina, which unilaterally declared independence from Serbia in 2008.
Angry local Serbs erected the barricades to prevent access to the border crossings after the Pristina government moved in September to put Kosovo Albanian customs and police officials on the border, fearing this would severely limit their access to Serbia.
The security of the Kosovo officials at the disputed border posts is currently guaranteed by KFOR and EULEX, which is mandated to oversee police and customs services.