I think it worked because it put pressure on the government. The government is not hugely supported everywhere, it would have had increasing pressure on its higher powers if sanctions continued. Do you remember the green movement?

This is very US centric but still interesting. http://iranprimer.usip.org/resource/green-movement

>The Green Movement reached its height when up to 3 million peaceful demonstrators turned out on Tehran streets to protest official claims that Mahmoud Ahmadinejad had won the 2009 presidential election in a landslide. Their simple slogan was: “Where is my vote?”