Given how many hacking groups don't like the US, the latter would tell us almost nothing about the attackers' actual identities and objectives.
Though if I was a hacking group with little interest in Iran, hitting a US-based target...I might make some pro-Iran noises, trying to confuse the attribution. Or to curry favor with China, Russia, NK, ...
(And I'm not ruling out a nation-state actor being directly behind this.)
Being sickened and angered by the killing of so many schoolgirls, who happen to be Iranian, makes you "Pro-Iran"? Strange world.
People and nations should expect that an attack will be met with an attack.
If a bully is hitting someone, one of the most effective ways of stopping it completely is hitting back.
"My team is right, your team is wrong. You must chose my team otherwise it means you're with them and so you're wrong and my enemy"
No, you can both be wrong and right.
Maybe they should start dealing with this in their own country before fighting against it in other places.