Birth Certificate

My entire family line has always been in Rome, my father (now deceased) moved to America, where I was born. He was never a citizen of America, only Italy. I do not have his birth certificate but I know he was born in Rome. My family still lives here.

How can I get his birth certificate, where do I go? I do have his Italian identification number which I was told I will need to find him in the government systems. Grazie Mille❤️❤️❤️