Wireless Sensor Networks (WSNs) consist of small nodes equipped with sensing, data processing and radio transmission units. A number of clustering, routing, power management and data aggregation protocols are specially designed for WSNs where energy awareness is an essential design issue. Due to the resource constrained nature of sensor nodes, innovative techniques are required to extend the network lifetime in WSNs. This paper proposes an energy efficient routing protocol to find the forwarding path between source and destination node using heuristic function and A search algorithm. Simulation results with OMNET++ show that our proposed protocol is efficient in terms of network lifetime, total energy dissipation and message throughput.