It is a little tricky. If Turkey were to attack Israel this would be outside of the NATO treaty obligations and Turkey would be on its own. If, however, Israel were to take preemptive action and attack Turkey inside of Turkey (not in Syria or Lebanon), this would trigger NATO’s Article of collective self-defense. This requires assistance but not military intervention. But if Israel were to attack Turkish troops in Syria or Lebanon, then this would again be outside of NATO’s obligations. If war started in Syria and then spread to Turkey, I do not know how NATO would address this.
NATO wouldn’t do sht. No NATO country would respond to an article 5 invocation if Turkey mobilised against Israel and then got attacked. Especially the US. They would be warned publicly to stand down or face the consequences alone.