I'm not joking this actually made me laugh
So you think Iran can handle Pakistan? Let's compare shall we:
Ground Forces:
Pakistan: 1.5 million troops and 3,000 tanks
Fight major CT operations as well as skirmishes with India and are designed to fight an enemy several times bigger. Tanks are better equipped and in larger quantities. General equipment is better than Iran's.
Iran: 2.7 million troops and 1,500 tanks
Fight minor CT operations and are trained to fight an enemy smaller then them. Also has less advanced tanks and in smaller quantities. General equipment is also worse.
Since Pakistani troops are already involved in major ops, they can only send a fraction of that 1.5 million, so Iran has it's chances a little more fair.
Draw.
Air Force:
Pakistan: 400 fighter jets
Consists of roughly 150 advanced F-16's and JF-17's. Rest are F-7's and Mirages, which are decent. Pilots are some of the best trained in the world, examples include MM Alam and Sattar Alvi.
Iran: 140 fighter jets
Consists of 70 advanced Fulcrums and Tomcats, and the rest are Phantoms and Northrop Tigers with one or two indigenous fighters.
Pakistan decisively wins.
Navy:
Pakistan: 8 submarines, 5 frigates, 5 destroyers, 3 MW and 12 CDC
Better equipped than Iranian navy, but smaller.
Iran: 32 submarines, 6 frigates, 5 MW, 254 CDC
Bigger, but less well equipped.
Since Iran has a bigger coastline, they can only send so many ships otherwise they would be vulnerable, so they only send a small portion of their force.
Draw.
Nukes:
Pakistan: 130, can hit all of Iran
Iran: 0
Pakistan wins decisively.
In a war, the PAF can quickly gain superiority and start to decimate the Iranian Air Force and make life hell for the troops. They could bomb major Iranian cities and afterwards Pakistani ground forces would pick up the scraps, and start some more war crimes like in 1971 (just being realistic, I wouldn't be proud of such acts). The Iranian navy might try to get some revenge, but the PAF can help the PN successfully defend the coastlines and do some major damage to Chabahar.
Even if somewhow Iran starts marching into Pakistan, Tehran will be nuked.
In a war, there is no way Iran can win. We don't want a war, but we are all being realistic about this.