The tunable mode conversion between symmetric and antisymmetric optical modes induced by acoustic flexural waves in optical microwires is proposed. The acoustic frequency dictates the resonant coupling between the optical modes, and consequently, the modes in which the mode conversion occurs. On the other hand, the efficiency of the mode conversion can be controlled by the acoustic wave amplitude. Moreover, symmetric modes can also be excited by a double resonant coupling between a symmetric and an antisymetric mode, and further between the antisymmetric mode excited and another symmetric mode, leading to a mode conversion between symmetric modes