When you apply for a visa at an approved Iranian travel agency, the agency will apply for your visa at the Ministry of Foreign Affairs (MFA). Upon approval of your visa, a visa reference number will be generated by MFA and faxed to the Iranian consulate nearest to your residence. Your tour agency will send you this reference number. You can hand over the reference number to the Iranian Embassy to obtain your Visa.
Please note: The visa reference number is an “authorization code” and means that your visa has been granted by MFA. You will use this number to pick up your visa at the designated consulate/embassy of Iran or have it posted to your address. For further information, please contact the Iranian Embassy closest to you.
bellow is the list of world wide Iranian Embassies for Iran Visa