A non-theocratic Iran is in the US interest.
If you give the Iranians arms, I’m sure they would be happy to fight. Have we armed anti-regime Iranians?
I do think we have an obligation to help. That’s just my personal opinion.
As an analogy: if your neighbor is beating his wife, it’s not moral to just put your earplugs in and go back to sleep. You have to take action.