Salaam
The Iranian are simply antagonising the Taliban as well Pakistan. Pakistan is generally averse to acting against Iran but the Taliban may not be so.
If the Iranians try to create problems for the Taliban, the Taliban are likely to find may backers willing to fund them to create problems for the Iranians.
Regardless, Pakistan needs to fully fence and monitor our borders with both Iran and Afghanistan. Use technology - drones etc - to ensure maximum coverage. Things could get heated between the two.
I also feel in case of Iranian aggression, the Taliban will have motives to remain friendly with us. It could help increase Pakistan's leverage on the Taliban and their government.