That's not exactly true. People tout those photographs of "liberated" women in Iran in the 70's but that was a tiny slice of a female urban lifestyle restricted to a small number of elite women. That was not representative of the lives of the overwhelming majority of Iranian women.
Iran was still far more liberal in general before the cultural revolution, no? Women don't have to be in nice clothes in urban areas to not be repressed by clerical rule backed by state rule... There may have been societal pressure but it's significantly different when it's backed by government security services and religious police.
Yes, the Shah of Iran pushed a massive modernisation program [aka liberal agenda] to westernise Iran. The pushback from conservative elements was one of the driving forces of the revolution.
The interference from western powers to prop up the Shah did not help matters.
At least this was the impression I got from my time in Iran and visiting the tourist sites.