"The negotiations in Istanbul are not for a compromise peace on unrealistic terms someone has come up with, but for our swift victory and a complete destruction of the neo-Nazi government", Medvedev writes on the messaging service Telegram.
He addresses the message to "all who are worried and waiting for revenge".
On Monday, a second round of peace talks between Ukraine and Russia in Turkey. The meeting ended after an hour with an agreement on prisoner exchanges between the countries.
Ukraine is said to have proposed an unconditional ceasefire, but Russia is said to have rejected the proposal.
