Iranian official calendar, regulated according to Solar year & Iranian months .21 March, equal to 1st of Farvardin, is beginning of Iranian New Year. Also in Iran, Lunar calendar is announced officially. Lunar year is 10 days less than Solar year, so days of performing religious rites, that adjust according to Lunar calendar, each year is different from next & former years.
Therefore it is recommended to tourists to arrange their proper traveling time with the related agency, especially in Ramadan month that Iranian Muslim are fasting and in Muharram are mournful, so these situations influence on daily & current activities and somendays in these two months are public holiday. Friday is the official holiday.