"The choice now faced by British political leaders who have advocated Brexit is to renounce their absurd political promise or face economic disaster, with the British people the main victims," Le Maire said at a Paris forum on reforming the World Trade Organisation.
"What does Brexit demonstrate? It shows that leaving the common European market has an exorbitant economic cost," he said.
"There are a number of lying and irresponsible politicians in Britain who told the British people that Brexit would turn out to be a golden tomorrow," he added.
Le Maire's comments came as British Prime Minister Theresa May battles to salvage her draft Brexit deal and her own political future.
After a tumultuous Thursday in which several ministers resigned and members of her own conservative party plotted to oust her, May said in a radio interview Friday that she believed with "every fibre of my being" in the Brexit course.
Members of parliament on all sides have warned her there is no way the plan can win their approval, but she has dismissed calls to quit, saying: "Am I going to see this through? Yes!".
Critics of the deal say May has conceded too much to Brussels, while EU supporters are calling for a new vote on whether to leave the union.