We address the rendezvous control problem of a group of thrust-propelled Unmanned Aerial Vehicles (UAVs) interconnected over an undirected graph and subject to interagent constraints. The proposed distributed control law achieves the desired formation using only local information and guarantees inter-agent collision-avoidance as well as connectivity maintenance. Relying on the edge-agreement framework and on singular-perturbation theory of multi-stable systems we establish almost-everywhere practical input-to-state stability of the desired formation with respect to disturbances. In the absence of perturbations, asymptotic convergence to the consensus manifold is ensured. A numerical simulation illustrates the effectiveness of the proposed approach.