Today, there has been some upheaval in the Grand Bazar of Tehran, which is not only the heart of the city (and very worth a visit, it will completely overwhelm any first-time visitor), but also located right next to multiple government and justice buildings.
For those wishing to just decapitate the present government - please consider the effects of similar strikes in the past. Removing Saddam Hussein in Iraq has led to a civil war and until now, 22 years later, the country has not come to rest. Removing the Taliban in Afghanistan after 2001 was not entirely crowned with success either, Mubarak in Cairo has given way to as-Sisi, Qaddhafi to chaos and struggling factions, Tunisia is slowly sliding towards the next autocracy, and how Syria will develop under its present government still remains to be seen. Do not expect a fully developed western style democracy to rise from the ashes, and do not expect a country to gladly adopt a system forced upon it.
Building up a stable government against the countries traditions either takes massive violence or much time, patience and a gradually-decreasing, initially firm grip, as has been seen in Western Germany after WW2. There, the foundations of a democracy had been laid in the 1920s, so there was at least a little beginning of a tradition that could be built on.
For Iran, a proud, ancient country that has had foreign countries meddle with it for quite a few decades over the last centuries, it may well be advisable to let them sort it out on their own with only discreet, low-key support from outside.