Acting as God was not the issue. satan was trying to deceive Christ by tricking him into doing something satan claimed was ok but wasn't like how he twisted scripture to make it seem like Jesus could jump off a cliff and be saved by angels. Christ knew that was not what the scripture spoke about plus if he jumped and wasn't saved, he likely would die and not fulfill the prophecies like the Cross.
Actually I was thinking more about turning stones to bread. That is not a temptation for you and me, as we do not have that type of inherent power, but Christ did. While he did not function as God, it does not mean He stopped being God so even as a man He could utilize His own power to do such a thing if He wanted. However, if he had done so it would have been "against the rules" (so to speak) as he had to live and function solely as a man in order to die as a man for man.