It's not anyone's goal to overthrow Iran. No one want to clean up the mess. There are already enough messes in that region already (afghanistan, iraq, syria, yemen).
In 1953, the CIA baited the Iranian coup d'état by covertly supporting pro-shaw groups. The shaw was then overthrown in 1979, bringing Khomeini to power as the Supreme Leader. Our role in the later Iranian revolution isn't as clear, yet. After that the 2009 Persian Awakening was additionally supported by the states.
https://fas.org/sgp/crs/nuke/RS21592.pdf
The US puppet planning to start building 23 nuclear power plants in the 70s were based on US support to create a US friendly power-base in the middle east.
https://www.nytimes.com/2018/05/01/opinion/tehran-nuclear-sa...
...It's really worrying to me that the New Left seems to embrace nationalism and American exceptionalism just like the right. It means nobody is pushing back against creating wars. A lot of people will die for it unless people wise up.
Also the US does not have a great track record with inciting revolutions in Iran.
(just not intentionally)
Rather, sanctions attempt to align financial incentives of those in power with the country issuing sanctions. It may seem (thankfully) foreign to those in the West, but in autocratic places like Russia, Iran, and China, the people who control the policy of the state are generally also the people who have large stakes in the major economic engines of the state. Given that autocrats tend to be motivated by wealth at least as much as they are motivated by power, sanctions can force autocrats to try to negotiate with sanctioning countries, wherein the autocrat tries to adopt his policy as little as possible to the sanctioning country (so as to keep a grip on power) in order to get wealth flowing again.
They supported the Iranian revolution expecting they will be able to control the outcome. That was ending the British relationship and starting an only American one with their oil.
This worked out pretty well in Saudi Arabia, which was very primitive and had very small population.
In the end,though,in Iran they are Muslims first and Iranians second, with a long History. They could have accepted all the money from infidels that they could get, and promised whatever to them, but their own religion says they could(and should) lie to infidels. So they did it.
I'm not saying the world is/isn't a better place, just explaining the common beltway logic re: Iran sanctions.