Hi, I am from IRAN living in Sydney Austrlaia, flying from Sydney to Japan, with Air CHina,

Hi, I am from IRAN living in Sydney Australia, flying from Sydney to Japan, with Air China, which got 4 hours layover in Beijin (China) , if anybody know shall i apply for transit visa or not ? I wont leave the air port in china.( do you have any reference that i can refer to it ? ) I read in China embassy website, layover less than 24 hours in airport with international airline do not need to apply for any transit visa. ( so Does Air China classified as intenrational airline for them ? ) Thanks