I know I had a similar problem going to Uganda, when the Lord's Resistance Army was active and parts of Uganda were on the either the 'do not go to' or 'advise against travel' list (I'm sorry, it was a long time ago, I can't remember which ), which meant that many companies would not cover travel to Uganda at all, even though it was only specific bits of Uganda which were advised against.

In the event, I did a lot of small print reading and found one which had a less all-encompassing provision which meant travel to Uganda was covered - I got it through Boots though, and I can't remember who the primary insurer was.

You may need to get into the small print of a lot of companies. Also, be aware, travel to Iran does carry increased risk in the eyes of the insurance industry because of that warning, so you may need to pay more than the bog standard bucket and spade policy.

I also recall, after the conclusion of the Iraq war, and when it was thought it would settle down, some colleagues were sending staff out to Iraq. Insurance cost was £10k per person sent.... But that was a pretty extreme place. Things then got even worse, and they pulled out.