Pressure can work on the Iranian Regime. There has been, for more than a decade, a curious line of argument that pressure upon Iran is counterproductive
It’s important to remember there’s a huge disconnect between the Ayatollah and his henchmen who rule the country, and the Iranian people. Reza Pahlavi, the son of the late Shah of Iran, has been an outspoken proponent of a democratic Iran.
When we say "regime change," we're talking about giving moral support to the Iranian people against a regime of greedy, fascistic religious fanatics that is oppressing them. This can be done in a whole variety of ways, starting with making them know we care about them and have no interest in talking to or negotiating with their oppressors who just want to play for time.