Macron made the statement during a presidential debate with challenger Marine Le Pen.
Le Pen, who supports a full ban on the veil, said she was “not carrying out a war against their religion.”
“I am for the banning of the veil in public space. The veil is a uniform imposed by the Islamists, a large part of the young women who put it on cannot do otherwise in reality, even if they dare not say so,” Le Pen told viewers.
“What you’re saying is very serious,” Macron responded.
“You’re going to create civil war if you do it.”
However, polls show that the majority of the electorate side with Le Pen in supporting the banning of the veil.
A poll conducted last month showed 61 per cent were in favor of banning the veil.
A more recent survey found that 35 per cent were “totally for” banning the veil, while a further 25 per cent were “rather for” the move.