Under the law, platforms such as TikTok, Snapchat, Instagram and Facebook must verify users' ages and prevent those under 15 from using their services.
The law, which also bans mobile phones in French high schools, was passed by parliament by a wide margin in July and was due to come into force in September.
President Emmanuel Macron has tasked Prime Minister Sebastien Lecornu with drafting a new bill that takes into account both the Constitutional Council's decision and European law, the Élysée Palace announced. This will be done "as soon as possible."
