I personally am not well read on this, but I know lot of people blame the US and the UK since after they overthrew the democratically elected socialist government and installed a brutal dictator[0], the only elements that survived to oppose the dictatorship were hardened islamists, who later took power from the US backed Shah[1]
[0] https://en.wikipedia.org/wiki/1953_Iranian_coup_d'%C3%A9tat
This is basic, commonly accepted history. That’s why all of the comments defending US actions deflect and blame the accomplices within Iran like the Shah.