Which are safe and unsafe regions in Iran?

I am a New Zealander who travelled to Iran about two months ago, flying into Shiraz, visited Persepolis, and made my way north by bus through Yazd, a little village called Toudeshk, and Esfahan before reaching Tehran after two weeks. This is a very traditional tourist route through the central part of the country and is entirely safe for Western travellers. Avoid the border zones with Iraq and Afghanistan and you'll be fine. Iran itself internally is a stable country, with the people busy going about their lives and getting ahead. They are incredibly friendly and honest and who will go out of their way to help you. I found it safer than being at home at night in particular, as there is no drinking culture which leads to the random street violence common in Anglo-Saxon nations...

You will find lots of European travellers, the odd Kiwi and increasingly many from China. I didn't come across any Australians, Brits or Americans. It isn't just for adventurous young backpackers: in the big tourist spots (like Esfahan and Persepolis), there were hordes of little old ladies from Italy and Germany in particular on package tours.

Iran is a very easy place to travel in: you can get by with just a few pleasantries in Persian, as someone is always ready to help you out if needed. Get the Lonely Planet guide and you'll be well set up. You might want to check out this excellent travel blog from a Kiwi couple I met there: http://andotherdetours.com/category/iran/

I am an Iranian and maybe know more about my country, since I live here now.

Obviously, there are some places that are not safe, not only for tourists, but also for ordinary citizens. Places like Afghanistan or Pakistan borders, and some sectors in every city. You can ask someone in that city to tell you about those sectors.

Nowadays many people in Iran can understand English, although not fluently.

If we factor out those places, most parts of cities are calm and without something special. You may just find people come and go, some traffic, sometimes violence, sometimes kindness, some happy people, some sad people, and so on. But for a foreigner, it is important to respect some rules about Iranian-Islamic cultures. For example, don't drink alcoholic beverage in the middle of bazaar! Or don't shake hands with a lady, if you are a man. Surely, people won't kill you for these, but they look at you angrily. Especially if you are going to travel to small towns, try to respect their cultures more.

Iran is in general very safe, both for Iranians and foreigners. There is no war or fighting going on there, the crime rate is very low, and even when crime is committed they tend to be of a less violent nature than in most western countries. For people worried about safety, I would say the only place in Iran to avoid is the province of Sistan & Baluchistan which borders Pakistan. It's a predominantly ethnically Baluchi and Sunni Muslim region of Iran, so they are an ethnic and religious minority in Iran. I've never been but there are often stories of kidnappings, militants shooting at Iranian reservists or policemen, and there is also a fundamentalist Sunni Muslim group called Jundullah operating in that province.

Having said that, the province of Sistan and Baluchistan is probably not that interesting for most tourists to visit, so you won't be missing out on much if you opt out of going there. Other than that, everywhere in Iran is safe. Tehran is safe, the historical capital of Esfahan is safe, the Kurdish provinces are safe, etc.

Iran is definitely a safe place to travel. As long as you do your homework and research a bit before going, you'll be fine, even as an American.

source - I travelled in Iran with my girlfriend last December. the tour company we used had a post about this here http://lilontravel.com/en/safety-in-iran-is-it-safe-to-travel-to-iran/