Github does block functionality through Iranian IPs, and this is easily verifiable if you know anyone who lives in Iran and can access a website or via an Iranian proxy connection and then attempting to use private repos functionality on personal accounts, with enterprise accounts being entirely blocked.
Personal Gmail accounts are the exception to Google services available in Iran, and some functionality is also blocked by IP - if you live in Iran currently you might know that almost all other Google services and enterprise accounts are outright blocked by IPs too:
