Mr Tadic said he could not accept the dismemberment of his country and called for renewed talks on the issue.
The pro-Western leader was speaking at the opening of an annual security conference in Munich.
The US and most members of the EU say they will support independence for Kosovo's ethnic Albanian majority.
"Should Serbia be partitioned against its will... it could in turn result in the escalation of many existing conflicts, the reactivation of a number of frozen conflicts, and the instigation of who knows how many new conflicts," said Mr Tadic.
While he described Kosovan independence as unacceptable, Mr Tadic added that he did not want to see Serbia isolated from the EU.
"There is still time to prevent the situation from spiralling needlessly out of control," he told the gathering of the world's top security officials, urging international talks.
No good time
President Tadic is a leader who stands between a rock and a hard place. He is already being buffeted by an internal political crisis in Serbia, which he has admitted could well lead to new parliamentary elections in May. And now the Kosovan independence issue presents him with a major national dilemma.
Many diplomats in Munich expect the declaration of independence to be made around 17 February.
Mr Tadic's efforts to steer his country on the path towards the EU and the West were appreciated by the Munich audience, made up of prominent US and European policy makers. The president received warm applause, but is unlikely to have swayed many minds.
Western diplomats here say that months of talks have produced little.
Mindful of Russia's opposition, there is no good time for Kosovo to declare independence, one insider told me - it might as well happen sooner rather than later.
值得好好研究一下...
特別是近期網壇出了不少來自Serbia的好手
而且,為什麼Kosovo就可以獲得西方大國的支持,
而我們台灣卻永遠只能當國際上的孤兒!?
世界上少了Kosovo跟少了Taiwan,哪個影響比較大..?
答案自在人心。