"Kosovo will not gain independence. And no U.S. officials making daily statements in support of Kosovo's independence can obviate that fact," Vojislav Kostunica said, adding that Belgrade will never agree to a 15% reduction of his country's territory.
Kostunica said Kosovo would remain a component and integral part of Serbia, as written in the UN Charter and the country's Constitution.
The UN Security Council has been holding closed debates on a resolution drafted by Britain, the United States and France giving Belgrade and Pristina four months for more talks before automatically granting independence to Kosovo.
It is the third draft resolution based on special envoy Martti Ahtisaari's plan to grant Kosovo independence without the prior consent of Serbia.
Russia, a longtime ally of fellow Slavic Serbia, has insisted on a decision that would satisfy both Belgrade and Pristina, and threatened to veto a resolution setting the province on a path to independence.
Russia has said granting Kosovo sovereignty would violate Serbia's territorial integrity, setting a precedent for other breakaway regions, including in the former Soviet Union. It has also expressed concern about the future of the impoverished province's Serbs and other minorities, who number about 180,000 in all.
Kosovo Albanians have meanwhile warned they will take independence unilaterally.
Kosovo has been a UN protectorate since NATO's unsanctioned 78-day bombing campaign against the former Yugoslavia ended a war between Serb forces and Muslim Albanian separatists in 1999.