Demonstrators marched in support of Palestine in Paris and other cities, including Toulouse and Lyon.
Protesters urged Paris to take action to secure a cease-fire.
The march in Paris, which began at Republic Square, concluded at Nation Square.
Tens of thousands participated, including members of the La France Insoumise, a left-wing populist political party that includes MPs Louis Boyard, David Guiraud and Rachel Keke.
Protesters drew attention to the deaths of children in Israel's attacks as they carried small coffins covered in red paint and toy dolls, while some raised their red-painted hands in the air.
They carried banners that read: "Free Palestine", "Ceasefire" and "This is a genocide, not a conflict," and chanted: "Israel is a murderer, Macron is an accomplice", "Gaza, Paris is with you" and "Long live Palestine."