"In Israel and in Gaza, the situation is very hard," Fabius said as he arrived for a meeting of European Union foreign ministers.
"Nothing justifies continued attacks and massacres which do nothing but only claim more victims and stoke tensions, hatred," he said.
"France will act forcefully to demand an immediate ceasefire," he added.
French President Francois Hollande said yesterday that everything should be down to bring a halt to the fighting, now entering a third week.