Rebels have also fired rockets onto the capital.
Turkey has been battling the YPG in Afrin since January 20.
Turkey launched the military offensive against the US-backed Syrian Kurdish militia known as YPG, to clear its fighters from the enclave of Afrin.
"Right now we're getting reports - I don't have evidence that I can show you - but I'm aware of the reports of chlorine gas use", he said before arriving Sunday in Oman.
The Syrian military, backed by Russian forces, has in the past month pressed an offensive in eastern Ghouta aimed at reclaiming control of one of the last major areas around the country's capital that is still in the hands of opposition fighters.
Residents said dozens of people were still buried alive under rubble, with rescuers unable to reach them due to the intensity of the raids.
State television on Sunday broadcast from the eastern Ghouta town of Mudeira, which state television and a war monitor said the army had captured to link up with units on the other side of the enclave.
Eastern Ghouta, which is home to some 400,000 people, has been under regime siege ever since 2013. The expulsion of the rebels from eastern Ghouta would represent their biggest defeat since they lost their enclave in Aleppo in December 2016.
According to a UNICEF report released in the German city of Cologne on Monday, the figure includes 86,000 people who have had to undergo amputations. Douma is eastern Ghouta's largest settlement.
Jaish al-Islam, one of the main rebel groups in eastern Ghouta, said on Monday it had reached an agreement with the government's ally Russian Federation to evacuate wounded people. The group also did not say when the evacuations would begin or where the wounded would be taken.
"This is a debate we will have in the coming hours at the United Nations, where it will be shown that the concessions on the ground from Russian Federation, but first and foremost the Syrian regime and its Iranian allies, are insufficient", Macron said.
On Monday, Syrian forces pounded two rebel towns in Eastern Ghouta, pressing on with a Russia-backed offensive that has so far allowed government fighters to retake almost 60 percent of the enclave.
The UN Resolution 2401 that was unanimously passed by the Security Council on February 24 called on the parties to the Syrian conflict to stop all hostilities and adhere to a humanitarian pause across Syria in order to ensure the safe and unhindered delivery of humanitarian aid, as well as medical evacuation of those injured. "There's an bad lot of reports about chlorine gas use or about symptoms that could be resulting from chlorine gas".
The government denies using either incendiary weapons or chlorine gas bombs, and said on Saturday it had information that the rebels were planning to stage a fake chemical attack to discredit the army. "The cease-fire has failed".