GENEVA — Secretary of State John Kerry voiced support for Russia’s attempt to convene peace talks in Moscow between representatives of the Syrian government and the opposition, even though some leading opposition figures have said they do not plan to attend.

“We hope that the Russian efforts could be helpful,” Mr. Kerry said on Wednesday at the start of a meeting here with Staffan de Mistura, the United Nations envoy for the crisis in Syria.

Mr. Kerry also praised Mr. de Mistura’s attempt to broker local cease-fires in Syria, starting with the contested city of Aleppo, saying he hoped it could “have effect.”

Mr. Kerry’s support for the Russian and United Nations initiatives comes as the American-led push to negotiate a solution to the bloody Syria conflict, the so-called Geneva process, has faltered. The United States has not withdrawn its public insistence that no enduring political settlement is possible as long as President Bashar al-Assad is in power. Nevertheless, Mr. de Mistura’s step-by-step strategy to de-escalate the civil war is attracting growing interest among some Obama administration officials.