Luxembourg Prime Minister Jean-Claude Juncker said on Wednesday he was not convinced the time was right to find a definite solution to the status of Kosovo.
The United States hopes to open final status talks on Kosovo in September, provided the province in southern Serbia proves its democratic credentials.
"I'm not convinced the moment has come to solve the question of the status of Kosovo in a definite way," Juncker, who holds the EU's rotating presidency in the first half of 2005, told a news conference at the Council of Europe.
Kosovo, legally a province of Serbia, has been administered by the United Nations and NATO-led peacekeepers since 1999, after a bombing campaign that pushed out Serbian troops.
The United Nations took control of Kosovo six years ago and put its final status on hold. Final status talks would eventually determine whether Kosovo will become independent, as the majority ethnic Albanians want, or remain part of Serbia.
But before any talks begin, the United Nations has demanded that Kosovo meets standards on issues such as democratic institutions and minority rights.
A spate of bombings and shootings has hit the province since Prime Minister Ramush Haradinaj resigned last month to face war crimes charges at the U.N. tribunal in The Hague.