Image for representation.
Syria's High Negotiations Committee has decided to boycott the Russia-backed conference in Sochi.
The announcement was made public in a tweet.
The Syrian opposition accused Russia of undermining UN-led talks.
The peace conference will take place next week and is expected to see close to 1,600 Syrian representatives in attendance.
Russia has been in the process of steering a separate negotiating track in Astana, and now in the Black Sea resort of Sochi.
Russia backs Syrian President Bashar Assad's forces.
The boycott comes in the wake of escalating violence in northern Syria marred by Turkish attacks on the Kurdish-held enclave.
(With inputs from PTI)