Operators of micro-grid as privately-owned sectors try to optimally determine their energy supply strategy aiming at maximizing their profits. Smart grid infrastructures enable residential consumers to modify their electricity consumption in response to energy prices. Clearly, increasing energy tariffs have positive impacts on the operator's profit. Additionally, sensitivity of consumption to selling prices leads to demand reduction by increasing energy tariffs. Therefore, operators of micro-grids retain a tradeoff between energy tariffs and demand. This paper presents a game theoretical approach for operators of micro-grids to supply the required energy of price-sensitive clients. Additionally, the information-gap decision theory (IGDT) is used to handle the financial risk arising from the uncertain wholesale prices. Simulation results justify the performance of the proposed approach.