The Pakistan–Saudi Defence Pact is a defensive agreement, meaning Pakistan is committed to defending Saudi Arabia in the event of any foreign aggression. It does not imply that Pakistan would support Saudi Arabia in launching offensive operations against Iran or any other country. Moreover, there is nothing to “activate”, Pakistan already stands prepared to defend Saudi Arabia if required.
The war being forced upon Iran carries grave consequences for the entire region, particularly for developing & poor nations such as Bangladesh and Pakistan. It is a disaster.