No, he wasn't. Iran under Mossadegh was starting to get closer to the USSR, yes, but that wasn't why he was overthrown. The CIA overthrew him because the UK asked them to, because Mossadegh nationalised Iran's oil industry, which meant that the UK no longer controlled it and couldn't get all the cheap oil they wanted any more.but wasn't he an ally of Stalin?
No, there were no signs of violent reactions against Mossadegh, expect from the little clique that wanted the shah to become a dictator.