This wire is likely the bond wire and is part of the electrical system. While this wire is important it could be moved. The purpose of the bond wire as I understand it is to prevent the possibility of a buildup of static electricity or stray electrical current from building up on the gas line and creating a spark which could cause an explosion if there was a gas leak. Many homes I inspect do not have this bond wire in place. None the less it should be there so if you must move it be sure to put it back somewhere else. This wire should be securely fastened to the gas line and a copper water line or ground wire connected to the ground system in some way.