Multicast is an efficient transport mechanism for group communications and to support a lot of applications that require mobile nodes work as a group several multicast mechanisms have been proposed. However, due to the mobility of nodes, many control messages are required for these protocols and then overlay data paths in overlay can remain static. In this paper, we propose a robust overlay multicast on-demand protocol (ROMOP) using unicast routing stream table. Therefore, multicast data packets between group members are delivered through the shortest paths in physical networks and the data path in ROMOP can be managed without periodic control messages in the dynamic situation. Simulation results show that our mechanisms reduce the control overhead and thus the overall latency compared to existing multicast protocols proposed for MANETs.