[Updated at 5:26 p.m. ET] U.S. President Barack Obama said Monday that he and Russian President Vladimir Putin discussed the conflict in Syria and "agreed that we need to see a cessation of the violence, that a political process has to be created to prevent civil war."

In comments to reporters after almost two hours of talks, Obama said he and Putin had "candid, thoughtful and through conversation" about various issues including Syria and Iran.

On Syria, Obama said he and Putin "pledged to work with other international actors including the United Nations" and its special envoy, former U.N. Secretary-General Kofi Annan.

Obama and Putin are in Los Cabos, Mexico, for the two-day Group of 20 summit involving leaders of 20 of the world's leading economies.

The United Nations announced Saturday it was pulling back its unarmed monitors from Syria because escalating violence was  hampering the monitors' ability to observe and verify reports.

Syrian opposition groups say more than 13,000 people have been killed since President Bashar al-Assad's government started cracking down on anti-government protesters last year. The United Nations' latest estimate puts the death toll at more than 10,000. CNN cannot independently verify government and opposition claims of casualties because the Syrian government has restricted access by international journalists.