I'll bite (although it's already been touched on early in this thread). Nuclear armed countries are not attacked. If Iran had nukes, there would be no war - how exactly would that make the world less safe in your opinion?
As of now now nuclear armed countries haven't been attacked outright in full acts of war, but the CIA/MI6/Mossad crowd has been running black ops and drone strikes on Pakistan since Obama got into office after saying in no uncertain terms prior to his election that he would unilaterally attack them. Might be just semantics but I think there's a notable difference between attacks and an full scale war.
Not saying a nuclear Iran would not prevent war but the US is really pushing its limits more than ever now that the empire is in a prolonged downward slide and the Shanghai Cooperation Organization crowd continues to gain strength. Not to mention we're pretty much in a new Cold War despite most Americans thinking Russia somehow stopped their military R&D at some point and they're no longer a military superpower.
(Iran does have some modern stuff to contend with, including mirved anti-radar missiles, mach 3 sunburn missiles, the Kowsar, and they're also not dummies when it comes to big rockets. With the correct attack strategy they could definitely do some damage.)