The discrimination of terrorists is always a tough nut to crack. Crafting a strategy to tackle terrorism is way easy than defining 'who is the terrorist?'.
Pakistan, I believe, is once again in a state of confusion like in the immediate aftermath of 9/11. If Pakistan is to abandon this alliance, Saudi will become annoyed on the contrary we see a much more complicated scenario.
The neutral path that Pakistan can take at this point is to put his conditions before Saudi that if Iran and Iraq are not part of this alliance then we might not join or at least give full-fledged support to its missions particularly without having any definite and obvious blueprints of its targets.
Pakistan can demonstrate its neutral diplomatic stand and convince both the parties to become united. Diplomacy has power; lessons are bare before us.