Macron said Paris had established that the government of Syrian President Bashar al-Assad had used chemical weapons, including chlorine, on April 7 in the town of Douma.
Assad said that there had been no chemical weapons attack in Idlib, and that the opposition reports were a false flag operation and a fabrication aimed at justifying the U.S. missile strike against the Syrian government airbase. "Our teams work closely together", he said.
The Kremlin warned Thursday that the USA and its allies, who are weighing military strikes on Syria, to avoid any steps that could destabilize the situation there.
Germany wanted, however, to ensure "that all efforts are made to demonstrate that this attack with chemical weapons is not acceptable", she said.
The French president, who said he was in daily contact with President Trump, said any strikes would go after Syria's "chemical capabilities".
The agreement was announced on Sunday morning by Syria's government and its ally Russian Federation, just hours after toxic gases were allegedly released on Douma.
Amid the talk of military action, the Kremlin, a close ally of Assad, countered that more "serious approaches" were needed to combat the crisis. Mr Macron did not supply the source of his information.
The Syrian-American Medical Society, which operates in rebel-held areas, said more than 500 people had been treated for symptoms "indicative of exposure to a chemical agent".
It was the first public acknowledgement by Jaish al-Islam of a deal reached for Douma, their last rebel holdout in the Eastern Ghouta suburb of Damascus.
It remains hard to place an exact figure on the number of people killed and wounded Saturday in the rebel-held town of Douma, on the outskirts of Damascus. He spoke during a meeting with Ali Akbar Velayati, an aide to the supreme leader of his ally, Iran.
"If there is a chemical weapons attack - there must be a reaction from the worldwide community".