Most of what I know about Iran and nukes comes from episode 14, The Iran Deal Protection Racket.

But basically Ayatollah Khamenei issued a fatwa a long time ago declaring nuclear and chemical weapons haram and a threat to humanity, a stance he’s stood by since. A translation of one version of his statements:

We believe that besides nuclear weapons, other types of weapons of mass destruction such as chemical and biological weapons also pose a serious threat to humanity. The Iranian nation which is itself a victim of chemical weapons feels more than any other nation the danger that is caused by the production and stockpiling of such weapons and is prepared to make use of all its facilities to counter such threats. We consider the use of such weapons as haraam and believe that it is everyone's duty to make efforts to secure humanity against this great disaster.

And that’s just from Natopedia