Make a speech. Make ten speeches. then make some more speeches. Send people to the UN to put pressure on iran to knock it off. Meet with other presidents to make a group condemnation of the crackdowns. declare iran a “no fly zone” and get the UN to back it up. Send food and medical assistance. send UN observers. send sat phones and battery power to the protesters. Make it clear that no government dignitaries will be allowed to flee iran or be given assylum in any western nation.
There’s a lot he could do.
Make “what is billed as a ‘major’ speech.”