The Syrian National Council, which was formed as a government in exile in 2011, indicated it had little confidence the so-called Geneva-2 conference in Geneva would lead to a lasting peace.
"Nothing useful will come out for Syrians from attending the meeting," council spokesman George Sabra told Russia's RIA Novosti news agency.
The Geneva-2 talks have the backing of the United States and Russia and are aimed at bringing the rebels and the government together to hammer out a political settlement to the conflict. A starting date for the negotiations has not yet been set.
The Syrian National Council is a key member of the Syrian National Coalition, which has been recognized by the United Nations as the legitimate representative of the beleaguered Syrian people.
Sabra said the decision to withdraw from the talks was made Saturday by the council's secretariat. He blamed the seemingly lackluster international response to the conflict as a reason to skip the talks.
Sabra added the council, which is based in Turkey, would consult with rebel leaders inside Syria before deciding its next move.