Transparent optical Wavelength Division Multiplexing (WDM) networks are vulnerable to physical layer attacks. This work proposes a meta-heuristic based algorithm for the planning phase of optical WDM networks while considering the impact of high-power in-band jamming attacks. The proposed heuristic algorithm serves sequentially the connections in a particular order and the meta-heuristic algorithm, called Harmony Search, is used to find better orderings in order to establish the requested connections. The objective of the proposed algorithm is to establish the requested connections in a specific way that minimizes the impact of high-power jamming signals through in-band channel crosstalk.