Igor Smirnov, leader of the unrecognized republic of Transdnestr, said on Thursday it could not be reunited with Moldova.
"We are ready for talks," he said. "But I know that it will never be possible to reunite that which cannot be reunited."
New generations have grown up in the republic who know Russia as its defender, he continued.
"Don't forget that generations have also grown up in Moldova who have been taught that Romania is good and that Russia and Ukraine are bad."
He warned that the price of reunification would be "explosion, pain and funerals every day."
The Russian-speaking province of Transdnestr has maintained de facto independence from Moldova since a brief war in 1992, which erupted from a buildup of tensions following the breakup of the Soviet Union.
Tiraspol insists on independence, and even integration with Russia, while Chisinau says it is willing only to give Transdnestr autonomy within Moldova.