Well there is a reason for that,because from now on,almost every demonstration that greens want to hold would lead to violence.Last time they came the only thing i saw was some people burning banks,cars,attacking local markets and causing huge damage.
I don't know if you were in Tehran few days after election in 2009,but i can say almost 2 million people came in to streets in Tehran without any single violence happens.But you know in most countries there are a very little minority who benefits from violence and anarchy.On that day some very mysterious incidents happened that caused the demonstrations to turn a little violent.I think you will with me me that neither the security forces and government nor protesters would benefit from any violence as it could throw the country in to chaos.That's why I've always looked in some incidents like Neda's mysterious death with doubts and pessimism.Who do you think would benefit the most from incidents like that?The government or peaceful protesters?none of them.However i don't deny that government made some bad mistakes too.