Conservative senator Bruno Retailleau said the French President had turned his back on the Kurds following the capture of their stronghold Afrin by Turkish forces last weekend.
Mr Retailleau said in a statement: “While France has always supported the Kurds, Emmanuel Macron, by his deafening silence on the situation in Afrin, has abandoned them.
“It’s a 180-degree turn from France’s former position on Syria,” he said, adding that former left-wing president François Hollande had been “a lot braver” than Mr Macron.
He added: “France is reluctant to openly condemn Turkish president Recep Tayyip Erdogan, despite the fact he has violated international law and his commitments towards NATO [by launching a ground invasion in Syria], of which Turkey is still a member.”
In January, Turkey launched a military offensive against Kurdish fighters in the rebel-held enclave of Afrin to “protect” its border, adding fuel to Syria’s already burning fire.
Some 250,000 civilians have since fled the violence there, while dozens have been killed, as well as around 1,500 Kurdish fighters.
Turkey sees US-backed Kurdish forces known as the People’s Protection Units (YPG), which played a key role in the US-led battle against Islamic State (ISIS), as a Syrian offshoot of the Kurdistan Workers’ Party (PKK), a US-designated terrorist group that has been fighting the Turkish government for decades.
Mr Retailleau said: “The abandonment of the Kurds is a humanitarian mistake, because what we are witnessing right now is ethnic cleaning.
“It’s a political mistake because we are allowing armed groups back into Syria who are no better than Daesh [ISIS]; it is also a diplomatic mistake because we are forgetting about and abandoning our allies at a time when they need us the most.”
The Turkish president’s ultimate goal, he warned, is to “win back control of Syria’s border region to replace the Kurdish population”.
The YPG was driven out of Afrin on Sunday, after which Mr Erdogan pledged to expand his offensive along the length of Turkey’s shared border with Syria, and into other Kurdish-held areas up to the Iraqi border if necessary.
Turkey has described the parts of northern Syria under Kurdish control as “terror corridors”.
France, however, has not remained completely silent on the plight of the Kurds in Syria’s seemingly bottomless civil war.
Last week, French Foreign Minister Jean-Yves Le Drian said that Turkey’s border security concerns “absolutely do not justify” the scale of its military offensive.