The European Union on Tuesday lambasted Kosovo's closure of several Serbian banks this week, calling the move "escalatory" amid stalled talks between the Pristina government and Serbia.
The closure of six banks on Monday dismantled what was left of Serbian financial institutions in northern Kosovo, where many ethnic Serbs live.
Serbia-Kosovo tensions have simmered for months after Kosovo made the euro its only legal currency and effectively outlawed the Serbian dinar.
The move angered Serbia, which continues to finance a parallel health, education and social security system for Serbs in Kosovo.
The two sides have held talks in Brussels over the issue but not reached an agreement.
"In the continued absence of sustainable alternatives, this will have negative effects on the daily lives and living conditions of Kosovo Serbs and other communities eligible for financial transfers from Serbia," EU foreign affairs spokesman Peter Stano said in a statement.
"Monday's operation proves again that Kosovo authorities prioritise unilateral and uncoordinated actions rather than cooperation with its friends and allies," he added, calling the closures "escalatory".
Kosovo's Interior Minister Xhelal Svecla defended the closure of the Serbian-licenced Postal Savings Bank outlets, saying the move was meant to uphold the "rule of law and order".
The NATO-led KFOR mission based in Kosovo said it was informed "shortly before the commencement" of the operation, according to a statement.
"KFOR personnel were not involved in the execution of these operations," the statement added, saying KFOR "expects timely consultation on any action of the Kosovo Police or the Kosovo Security Force that could impact regional security".
Pristina has argued that Belgrade's payments to ethnic Serbs are not banned but that they should be made in euros.
Kosovo adopted the euro as its currency in 2002, despite not being a member of the European Union or its eurozone.
Animosity between Kosovo and Serbia has persisted since a war between Serbian forces and ethnic Albanian insurgents in the late 1990s that drew a NATO intervention against Belgrade.
Kosovo declared independence from Serbia in 2008, a move that Belgrade refuses to recognise.
Ethnic Albanians make up around 90 percent of Kosovo's population of 1.8 million people, but ethnic Serbs are the majority in several northern municipalities.