Yeah, I don't think Iran wants to move against us. It would be a turkey shoot and a big time slaughter. They prefer to hole up in defensive positions, or at least they should. We could blow them out but they will rightly surmise that we wouldn't want to suffer the losses required.
This is the early twenty first century, not the mid twentieth. our casualties would not be any higher than when we went into Iraq. Even in the mid twentieth century, an assault on a city without air superiority didn't produce much friendly casualties if you didn't care whether it remained intact.