This the website of the Embassy - http://www.iranemb.warsaw.pl/1/pol.htm 

The address is below:

Dział Wizowy
Ambasada Islamskiej Republiki Iranu
Ul. Królowej Aldony 22
03-928 Warszawa
Tel. 22 – 617 56 27 (hours 9 – 12)
Fax. 22 – 617 84 52

 I did everything by phone (talked to a very nice lady, Polish by nationality I reckon, she explained everything clearly, advised how to apply and collect the visa and so on, I talked to her several times, was really helpful)

I sent passport, an application form, money transfer proof from the bank and a photo  by DHL service and the passports with visas came back to me in the same way so I did not have to be there in person. The fee is 50 euro. I waited a week but there was a national holiday in Poland so probably it would have been quicker.