A spokesman for the European Aviation Safety Agency said airlines were alerted Tuesday of the possible launch of "air-to-ground and/or cruise missiles with the next 72 hours", urging them to take precautionary measures.
"Air France has taken the EASA information into account and modified its flight plans for affected destinations, mainly Beirut and Tel Aviv," the airline said, adding that it was monitoring the situation.
The EASA cited a risk of "intermittent disruption of radio navigation equipment" for commercial flights in the region in case of military action.
Most international airlines no longer fly to Damascus since the outbreak of the Syrian civil war more than seven years ago.
The heightened tensions follow reports of a new chemical attack in the rebel-held city of Douma, not far from Damascus, which has prompted a global outcry against the heavy civilian casualties from the Syrian regime's bombing campaign in the area.
US President Donald Trump said Wednesday that "missiles will be coming" in response to the alleged chemical attack.