Firstly, terror is a relative word. About 60% of the people in Afghanistan do not consider the Taliban terrorists, and about 1.5 million people in Kashmir do not consider freedom fighters terrorists. Nobody knows who the Jundullah really are, and what their goals are.
Secondly, Iran is an "ally" that has provided anti-Pakistan Baloch insurgents with safe havens. Despite this, however, Pakistan has absolutely no interest in "nourishing" "terrorism" inside Iran. If the Jundullah does have connections across the border, then the onus is on Iran to stop them as they have absolutely no real establishment in Pakistan. Unlike India, Iran cannot even make a case for "state-sponsored terrorism".
Lastly, Pakistan is currently Iran's only friendly neighbor. If Iran decides to turn on us without thought, well, the consequences can be very negative. The same goes for India.