Foreign minister says meeting to be held in Paris to confront strategy of "total war by Syrian regime and its allies".
France has accused Syria and its allies of using political uncertainty in the US to launch "total war" against opposition-held areas in the country and called for new sanctions on Bashar al-Assad's government for the use of chemical weapons.
Making the accusations after a weekly cabinet session on Wednesday, Jean-Marc Ayrault, France's foreign minister, said that countries opposed to the Syrian president would meet soon.
Donald Trump's inauguration as the new US president will not happen until January 20 next year and President Barack Obama's outgoing administration is not expected to take an active role in Syria so close to leaving office.
European diplomats have expressed concern that Assad may feel emboldened by Trump's pledge to build closer ties with Russia, Syria's ally.