The Kremlin says it is acting on request of the Syrian government of President Bashar Assad. The United States opposes Assad and has questioned Moscow's assertion that it is targeting Islamic terrorists, saying the areas hit close to Homs are strongholds of the moderate opposition to Assad.
World leaders also tried to address the crises in Libya and Yemen with high-level meetings on Friday.
U.S. Secretary of State John Kerry and U.N. Secretary-General Ban Ki-moon urged Libya's two rival governments to come together and make the final step toward a peace deal.
But talks between representatives of the two governments on the sidelines of the U.N. gathering of world leaders have not yet resulted in a signed agreement.
Ban said a final draft is in the two sides' hands, and "the time for reopening the text has passed." He said the U.N. envoy for Libya, Bernardino Leon, has assured him that the parties "remain committed and will not go back on their word."
Kerry told the meeting that he hopes the process can be "completed in a very small number of days."
The oil-rich north African country has slid into turmoil since the 2011 overthrow and killing of longtime dictator Moammar Gadhafi.
Also set to address the General Assembly on Friday was interim Burkina Faso President Michel Kafando, who was arrested by members of the elite presidential guard during a short-lived coup and then released last month.