The visit by Ali Larijani, the head of Iran’s top security body, came as the Lebanese government moves to disarm Hezbollah, the militant group that has long been Tehran’s most powerful regional ally.

No group in Lebanon is permitted to bear arms or rely on foreign backing, its president told a visiting senior Iranian official on Wednesday after the cabinet approved the goals of a U.S.-backed roadmap to disarm the Iran-aligned Hezbollah group.