Unlike Israel, Iran is a member of the Nuclear Non-Proliferation treaty. Meaning that if Iran wants to pursue nuclear weapons (which, to be honesty, they probably do) they have a long way to go, both politically and engineering wise. It also means there are many ways to prevent Iran ever getting one (the Iran nuclear deal was a good example until Trump cancelled it).

Israel, however, is not a member of the Non-proliferation deal, and very likely are own a few nuclear weapons. If anyone is are afraid of Nuclear Weapons, they should not support Israel under any circumstances.