We propose and analyze a hierarchical agent-based secure multicast (HASM) algorithm for efficiently supporting secure mobile multicast in wireless mesh networks, with design considerations given to minimize the overall network cost incurred by multicast packet delivery, mobility management, security key management, and group membership maintenance. HASM dynamically maintains a group of multicast agents running on mesh routers for integrated mobility and multicast service management and leverages a hierarchical multicast structure for efficient multicast packet delivery. The regional service size of each multicast agent is a key design parameter. We demonstrate via model-based analysis that their exists an optimal regional service size that minimizes the overall communication cost. Through a comparative performance study, we demonstrate that HASM under optimal settings significantly outperforms traditional algorithms based on shortest-path trees and static agent-based multicasting extended with mobility management and security support.