Method of regulating the frequency of a resonator mechanism around its natural frequency, this mechanism including an elastic return means with a balance spring or a torsion wire, wherein a regulator device acts on this resonator mechanism with a periodic motion, with a regulation frequency which is comprised between 0.9 times and 1.1 times the value of an integer multiple between 2 and 10 of this natural frequency, controlling a periodic variation in the real part and/or the imaginary part of the rigidity of this elastic return means, this method being applied to a timepiece movement comprising a resonator mechanism of this type and including a regulator device arranged to control a periodic variation in the rigidity of this elastic return means.