With regard to the vast amounts of gas resources in Iran and ease of constructing gas plants, these plants have been widespread in the recent years. Among the problems of gas plants include air pollutions, high operation costs, limitation of natural gas grid, and more importantly gas outages during the winters. In winter season when gas outages occur, water resources can cover the mentioned drawbacks, however in summer they might not be accessible due to sultry weather conditions. Therefore, water reservoirs should be optimally consumed over the year. To solve these problems, a novel short-term coordination security-constrained unit commitment scheduling is proposed in this paper. The scheduling by coordinating sequential hydro-power and gas power plants, and considering the constraints of natural gas transmission system supplies the required system load. The proposed model is a nonlinear model that is converted to a linear mix integer model and solved by game theory and GAMS software. The presented model is implemented on a standard IEEE 6- bus test system. Simulation results show the proposed method ability to reduce the cost and operation coordination of cascade hydro and gas units with all available constraints.