Iran is a signatory of the Nuclear Non-Proliferation Treaty. Note the absense of Israel.
In fact, Iran is not developing a nuclear weapon.
Panetta: Iran is Not Developing Nuclear Weapons -- News from Antiwar.com
Israel is in direct violation of countless UN resolutions.
Israeli violations of UN resolutions
Here's what Israel does to anyone who A: converts and/or B: talks about their nukes
Oct. 5, 1986: Israel's Secret Nuke Arsenal Exposed
Israel Continues To Develop Nuclear Arsenal | Occupied Palestine |"A report publish by the Guardian British paper in London on Monday morning revealed that Israel to working on developing its nuclear arsenal, seeking to develop intercontinental ballistic missiles, and wants to boost its “second strike” nuclear power."
...Khalid M. Amayreh"Just imagine if control over Israel’s nuclear arsenal is passed to Talmudic, religious fanatics, Dov Lior, Ovadia Yosef or other Talmudic sages who believe that annihilating a million or two million non-Jews shouldn’t raise any eyebrows since non-Jews are effectively animals walking on two legs according to some influential rabbinic authorities."
"Israel now has over 400 nuclear and hydrogen weapons."
Israel nuclear weapons arsenal