Iran is a country that animal products are popular and consist the most part of the people diet. So being a vegetarian is not normal in Iran and finding restaurants serve this kind of foods are not popular specially in small cities. Anyway nowadays more and more young people are going to change their diet and use more planet based food daily.
By the way, In Gilan you can find many local foods that is based on vegetable.
Also most of Ecolodges, prepare a proper dish for tourists based on their diet.