In cloud computing environment, static configurations can provide for the attackers an environment too easy for exploitation and discovering the network vulnerabilities in order to compromise the network and launching intrusions; while dynamic reconfiguration seeks to develop a virtual machine (VM) migration over the cloud by applying unpredictability of network configuration’s change, and thus improving the system security. In this work a novel approach that performs proactive and reactive measures to ensure a high availability and to minimize the attack surface using VM migration is proposed. This interaction between attack and defense systems was formulated as game model. As result, we have calculated the Nash equilibrium and the utilities for the both attacker and defender, evaluate the parameters which can maximize the defender’s utility when the VM migration was planned and identify the potential attack paths. Therefore, the effectiveness of the game model was validated by some numerical results that determine optimal migration strategies in order to ensure the security of the system.