He called on the current government to reject pressure from the EU, Radio B92 reported.
Kosovo, a region where Muslim ethnic Albanians predominate, declared independence from Serbia in February 2008. While only 69 states recognize the Republic of Kosovo, they include a majority of EU members.
Kostunica described Kosovo as a "fake state." He said the Serbian government should resist efforts to change a proposed U.N. resolution on Kosovo to suggest a goal of good relations between the two neighbors.
"Not only is it not true that Kosovo and EU are separate subjects, but the truth is that Serbia is being conditioned in the most direct manner to pay with its territory for a continuation of the already, in many ways, uncertain EU integrations," he said.