She's alleged to have been an officer in a company that disobeyed American prohibitions on trade with Iran.

Calling it "bank fraud" is just a way of avoiding the question of what she did that was wrong. Who's arresting Anish Kapoor and his co-conspirators for committing fraud against Stuart Semple?

I haven't read the indictment, but isn't the allegation that she's an officer of a firm that exported restricted US-made HP telcom equipment under agreement with the US government not to share that equipment with Iran, and used a shell company in HK to transfer that equipment to Iran? My understanding is they snapped her up on the money side of the transaction because her hands were more directly there and that part is easier to trace. She needed to perform banking fraud in the US in order to make payment in the US for the US-made equipment. I believe the allegation is that she knowingly flat-out lied to HSBC about the nature of the HK shell company in order to get HSBC to complete the payment in the U.S. At least, that's my understanding. Am I missing something?

It's not like she was simply on vacation buying tourist kitsch in Tehran or selling Hwawei equipment to Iranian companies. I believe the allegation is that both the equipment export and the payment sides of the transactions touched US soil and violated US law.

You really should go read the indictment.

I've read it, and just went and read it again. I agree with GP.

But she did intentionally lie to the banks which, based on this lies, committed actions that they could be prosecuted for.

The validity of the iran embargo does not play a lot into this.