PARIS—The French government aims to strengthen antiterrorism laws and boost security at places of worship, French President François Hollande said Sunday, after authorities mounted a series of raids against an alleged Islamic terror network suspected of targeting France's Jewish community.

Police swept across France over the weekend—from the northeastern city of Strasbourg to the Mediterranean city of Cannes—taking at least 10 people into custody, and killing one man suspected of participating in a grenade attack last month...