The United States is working on "specific initiatives" to reduce violent attacks in Syria, particularly to stop the bloodshed in the province of Aleppo, according to the US State Department.
State Department spokesman John Kirby said on Saturday that US Secretary of State John Kerry has talked on phone about the issue to UN Special Envoy for Syria Staffan de Mistura and with Riyad Hijab, who is a negotiator for foreign-backed opposition groups.
Kerry had also asked Russia to pressure the government of Syrian President Bashar al-Assad to stop "indiscriminate aerial attacks" in Aleppo, Kirby said.
"In both calls, the secretary underscored that the initial efforts to reaffirm the cessation of hostilities in Latakia and Eastern Ghouta are not limited to these two areas and that efforts to renew the cessation must and do include Aleppo," he added.
The United States on Thursday demanded that Russia prevent the Assad government from conducting airstrikes against foreign-backed militants, reports said.
Washington expressed outrage over an airstrike on a hospital in the Syrian city of Aleppo, leveling accusations against Damascus and Moscow, which were flatly dismissed by both as unfounded.
Russia and Syria rejected allegations that their warplanes had targeted the hospital in the northwestern Syrian city, with Moscow suggesting that the US-led coalition was instead responsible for the incident.
Since March 2011, the United States and its regional allies, in particular Saudi Arabia, Qatar and Turkey, have been conducting a proxy war against Syria.
The UN special envoy estimates that over 400,000 Syrians have been killed in the conflict, which has furthermore displaced over half of Syria’s pre-war population of about 23 million.