The USN doesn't deploy all twelve Carrier Battle Groups at once, this would be require massive resource/monetary spending as well as domestic political support for such an undertaking.
And no, a single American carrier group doesn't have enough firepower to outgun Iran (nuclear weapons shouldn't be factored in), Idk where you're getting this idea from. Iranian domestic weapons manufacturing has been exponentially producing powerful and numerous quantities of game-change PGM (precision guided munitions) for quite some time now. Thousands, upon thousands, upon thousands of difficult to counter BMs, and Drones are being produced and fielded by Iranian forces. This isn't something that can be simply dismissed just because America has a carrier battle-group in the vicinity. -- Both the range of IRGC AshCM, AshBMs, Drones (UVAC, loitering, suicide, reconnaissance), submarine/ surface-vessel launched weapons would be enough to see American NAVAL based sortie rates reduced since they would be forced to operate further away from Iranian soil.
Iranian offensive assets on Iranian-soil are well-defended in vast, well guarded (both passively and actively) mountain bases. Mobile launchers also play a great deal in ensuring that any efforts to attrite such assets (mobile TELS) will be greatly circumvented due to their ever moving nature.
I hope your confidence is well placed. I would certainly welcome anyone who can give Israel a bloody nose.