Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb(-1). The measurements were made in the kinematic range Q(2) < 1 GeV2, 0.20 < y < 0.85 and x(IP) < 0.025, where Q(2) is the photon virtuality, y is the inelasticity and x(IP) is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, E-T(jet), were required to satisfy E-T(jet) > 7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5 < eta(jet) < 1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton.