Under bilateral agreements, Russia's Black Sea Fleet has the use of the Crimean Sevastopol base until 2017. Ukrainian President Viktor Yushchenko announced in the summer that Ukraine would not extend the lease beyond that date.
Russian Foreign Minister Sergei Lavrov said on Wednesday that Moscow would be ready to discuss the extension of its naval presence in Sevastopol, Ukraine "at a later stage."
"The position of our country remains immutable: Russia's Black Sea Fleet must leave Ukraine's territory after May 28, 2017," a ministry spokesman said.
He added that Ukraine's Constitution did not permit the establishment of foreign military bases on its soil.
Yushchenko has called for the Russian navy's early withdrawal from the Sevastopol base, as well as tougher deployment requirements and higher fees, demands that have not been backed by his former coalition ally, Prime Minister Yulia Tymoshenko.
Ukrainian Defense Minister Yuriy Yekhanurov has also ruled out the possibility of extending the lease.
Tensions between Russia and Ukraine rose after several Black Sea Fleet warships dropped anchor off the Georgian coast during and after August's armed conflict with Tbilisi over breakaway South Ossetia.
In a bid to appease Kiev, Russia has said it may submit an array of attractive proposals to Ukraine.
Russia's naval base in the Crimea currently has 50 warships and patrol boats, along with around 80 aircraft, and employs coastal defense troops.
