Macron delivered the warning in a telephone call with Russian President Vladimir Putin.
The Syrian government has repeatedly denied using chemical weapons and said it targets only armed rebels and militants, although plenty of allegations have been made during the bloody Syria civil war.
Ambassador to the United Nations Nikki Haley condemned the Russian government following those reports of Syrian government attacks on civilians using chemical weapons.
Ambassador Haley also made remarks condemning a Russian draft resolution at the U.N. Security Council intended to address the chemical weapons issue.
France and the United Nations have repeatedly called in past months for a Syria ceasefire and the opening of aid corridors to alleviate the region’s humanitarian crisis.