This is a common question from trekkers wishing to undertake a trek in Iranian nature.
Basically, it depends on where you are, who your guide is and how likely it is that you come across locals.
Shorts are not allowed for men or women alike. Short sleeves are OK if you are a man and also OK if you are a woman provided women have a long sleeve handy to put over their T shirt and a hat or a head scarf which they put over their head when passing villages or coming into contact with locals. The minimum dress code for women in the urban areas i.e the long overcoat is not compulsory in nature. If you are in very remote areas where coming into contact with locals is highly unlikely then you may wear shorts which cover the knee but remember the exposed parts o your legs will be more prone to bites ans sunburn. Asking your guide is a good option but you need also to consider that some guides are more conservative than others.
And we crossed that bridge!
We then had to negotiate our way through some steep rocky trail to get to the "flat" part of the trail grabbing whatever piece of rock we could. For the next time we decided to have fixed ropes installed although we doubt there will be a next time as this area is so pristine and the nomads so authentic and their culture so untouched that we would hate to contaminate that. Beautiful oak forest of the southern Zagros with lush green meadows, interesting looking limestones carved out by the forces of nature are is our vista, there is one that must be 25 m high in the shape of a mushroom, amazing!. We climb up a very steep scree only for Mehdi to tell us that we have taken the wrong path ! It is getting dark. We wait and he continues to see if he can find the trail leading to the first nomadic settlement, they call these Maal. Last time he came to this area was over 5 years ago so he could be forgiven for mistaking the path. Soon he comes back telling…