Spherical dielectric microdroplets are known to be high- quality optical microcavities due to the existence of the quasinormal electromagnetic eigenmodes, usually referred to as morphology-dependent resonances (MDR's). These modes are the subject of considerable interest owing to their significant influence on such optical nonlinear scattering effects, as SRS, SBS, lasing. The resonant properties of a microcavity strongly depend on its shape. It was experimentally established that the distortions of droplet shape cause extra-leakage of MDR's-photons through droplet surface bulges, and hence, the spoiling of its Q-factor. The shape deformation can be simply caused by thermal fluctuations of liquid, or induced by a laser pulse due to ponderomotive effect, and have been observed in several experiments. The main purpose of the paper is theoretical investigation of the ponderomotive deformations of spherical droplets and their influence on radiative energy balance of MDR's. The task is considered on the basis of first-order perturbation approach to the boundary problem of oscillations of dielectric sphere in the electromagnetic field. The numerical simulations have confirmed experimentally observed fact that when the train of picosecond laser pulses is acting on the droplet the maximal surface displacement occur in the region of the so-called Descartes ring on the droplet shadow hemisphere. The radiative energy extra-losses in this region are caused by surface bulge, are proportional to its amplitude and lead to a decrease of the cavity Q-factor.