"Most importantly, the support should be unanimous, including from Washington's side," Andrei Kelin said adding that this could be crucial for the conflict's resolution.
"The US is the only country that has not supported immediate ceasefire," he said.
Kelin expressed hope that Washington will enhance Kiev's decision-making to stop combat operations.
Putin on Wednesday unveiled a seven-point peace plan for eastern Ukraine urging the conflicting sides to end offensive operations. He also called for the pullback of armed forces out of shelling range of civilian areas, an end to airstrikes, an exchange of all detainees, opening of humanitarian corridors, repairing damaged infrastructure and deploying international observers to monitor the ceasefire.