alucard, it's useless. The mentality here in the USA, is that merely stepping off the sidewalk there results in heads-being chopped off. When movies like Lawrence of Arabia, Raiders of the Lost Ark, etc... get long-since seared into our images, it's not going away. Then combine that with the usual md'r notions of extreme caution for laws EVEN HERE IN THE USA (where some md'rs think you can be ticketed for merely detecting a sandbox without permission), and the combination is going to spell "certain doom" . I think the average md'r in the USA thinks that only in the USA and Britain can you detect in the world. Notice I'm not saying that md'ing in any other place is "necessarily ok", but just saying that there is a popular lore that only makes this psychology worse in some places.
I have yet to see anyone here come up with a law from Iran that truly said "no md'ing". I'm sure someone could find something about cultural heritage (no doubt), same as you/they could probably no doubt find cultural heritage verbage for any place in the USA too. So the bottom line doesn't really seem to be about "can I metal detect in Iran", but more-so along the lines of swashbuckling and heads-being-chopped off for merely chewing gum or something.