To do this, I would seek to destroy the fundamental bedrock on which the Iranian regime was built - religion, more specifically a certain interpretation of the Koran and the Muslim faith.
I would first create images and videos of the leaders of the Iranian government, past and present (Khomeni, Khamenei father and son, etc.), naked, some with bodies of naked women (because nothing upsets the patriarchy like trans-sexuality), drinking alcohol, dancing and fornicating, preferably not just with each other, but also with pigs.
I would then print the static images on paper, and create a fleet of small, lightweight drones equipped with video-projectors and loudspeakers, and use these drones to deliver the aforementioned images all over Iran, particularly in large metropolitan centers and in areas with large concentrations of Iranian troops, perhaps accompanied with messages like "God is Love" and "Free Iran".
I would play music to accompany this lewd choreography, ideally decadent Western music - currently, I'd recommend "I Love You Always Forever" by Donna Summer, "Face Down Ass Up" by DJ Isaac, and Beethoven's 9th particularly the Ode to Joy, although I'm sure there are a LOT of other great options out there.
Music could also be delivered in the form of small loudspeakers, similar to the mini JBL models, dropped by the drones in a way similar to how bombs are dropped by airplanes. The reigious beliefs of the Islamic Republic prohibit music. Drop a bunch of loudspeakers playing music all over Tehran, and you force them to respond, via expending manpower and money to remove those sinful devices, whilst keeping civilian casualties at zero.
And then I would keep showing those images, with the music, over and over and over, day after day after day, night after night after night until the Iranian regime realize that perhaps their theological beliefs need some revision.
If a regime is willing to kill women brave enough to show their hair in public, how will they react when they see their national heroes and founding fathers naked... with women's bodies, no less?
But while you can kill a human being, images cannot be killed. What has been seen cannot be unseen, and even the drones, if they are small and light enough, like mosquitos, will be so costly to destroy that the regime will be unable to stop them.
Their entire raison d'etre, the enforcement of a highly patriarchal, extremely traditional interpretation of the Koran via violent coercion, will no longer exist, because every single day, their army and their people will be confronted with what they've been attempting to destroy their whole lives - human sexuality. Female nudity. Alcohol, music, dancing, sex, including with animals deemed most unholy. And the worst part? It actually looks like a lot of fun :D
Of course, breaking the legitimacy of the current Iranian regime would not necessarily lead to their replacement.
If, despite being the targets of ridicule, the current regime would persist in violently oppressing the people of Iran and generally being a bothersome nuisance on the international stage, then the second step would be to simply arm the Iranian population.
Given the relationship that the Iranian government has with its people, is there any reason not to drop hundreds of small arms into the streets of Tehran and other large Iranian metropolitan areas in the hopes of engendering an armed revolution?
If the people of Iran are brave enough to stand up to the armed thugs that oppress them unarmed, imagine what they'd be able to do if they actually had guns.