The warning was communicated through the existing deconfliction channel, the spokesperson confirmed, without giving any details of the missile attack.
Pentagon also said that United States did not target the sections of the airbase where Russian forces were believed to be present.
US President Donald Trump's national security advisor Herbert McMaster said that the United States has gone out of its way to minimize Russian casualties during the Thursday US missile strike in Syria, but there are no guarantees.
"US took great pains to avoid Russian casualties in Syria but anytime in a military operation, there are no guarantees," McMaster said after the missile attack.
Also, US Secretary of State Rex Tillerson claimed that Russia had failed to carry out 2013 agreement to secure Syrian chemical weapons, saying that Moscow was either complicit or incompetent. "We sought no approval from Moscow," Tillerson said.
Earlier US President Donald trump authorized the launch of dozens of Tomahawk cruise missiles at the military airfield in Ash Sha’irat 38 kilometers southeast of the city of Homs, claiming it was in "vital national security interest" of the United States.
The Ash Sha’irat airfield reportedly used to serve as an advance airfield to refuel Russian military aircraft.
