A system for actuating a member for dispensing a fluid product has a push button and a body having a well for mounting on a tube for supplying the member. The push button is axially movable over an actuating course of the member. A locking device reversibly locks the actuation by preventing movement. The locking device has an insert mounted in the bushing with the option of relative rotation, the insert having means for connecting to the member for conjoint rotation and at least one deformable stop. The locking device has a structure connected to the bushing for conjoint rotation and is arranged, by rotating the bushing relative to the insert, to deform the stop between an active state in which said stop is arranged on the actuating course to interfere with the body and an inactive state in which said stop is at a distance from the course.