Hi welcome to the Community,
Maybe you should try to put more light. did the Pakistani embassy Embassy state the reasons why they refused to grant you the Passport and the Certificate of Nulla Osta?
Because it's basically impossible to Marry in italy without providing your Passport and the Certificate of Nulla Osta (Certificate of no impediment) the reason is that the Italian registry office where you intends to marry won't be able to prove your identity and your capabilities of contracting legal Marriage.