Mobile Ad-hoc Networks (MANETs) are important in pervasive computing systems, in which users discover and utilize various services to achieve their goals. Integrating service discovery with efficient route discovery protocol in MANETs can greatly improve the efficiency of pervasive computing systems, and hence an efficient route discovery protocol in MANETs is desirable. In this paper, a Location-based Directional Route Discovery (LDRD) protocol with a node location service based on local coordinates in MANETs is presented. In our LDRD protocol, route discovery is only performed in allowed areas using directional route requests. This LDRD protocol is shown to greatly reduce the overhead of route discovery, and improve the efficiency, adaptability and applicability of MANETs in various types of network scenarios.