This is exactly what Pakistan doesn't understand: Foreign Policy.
International affairs are not like a boyfriend-girlfriend relationship.
There is trade and business and then there is strategic interests.
When your jurnails signed the security treaty with Saudis, you obviously agreed to some close-ended deals as did the Saudis.
No one will know it in public, but it would definitely mean that both of you have some restrictions over the other.
We don't have any such agreements with anyone (including US, which is more of interoperability and logistics cooperation agreements rather than committed coalition warfare).
Saudi Arabia has cordial commercial ties with us and we welcome it just as we welcome friendly strategic ties with Iran.
What Saudi and Iran have as an issue
is between them. It has nothing to do with us. We will never get involved in their fight.
Your terror groups go and kill Iranians and shiites across Iran. What does your government have to say for the brutal bombings that killed Iranian soldiers in their military parade in 2016?
As a nation under the influence of both Arabia and Iran (you have both sunnis and shias), you should try to avoid taking sides and mediate between the two.
But instead, we kuffars are having to play the fair game.
Don't take them seriously.
They don't understand that in international affairs, you don't need to take sides and can have good relations with more than two countries at the same time.