China won't be happy to be left alone, without the partnership of Russia, with the bad guys, with the axis of evil. China has its' own bad guys in the neighborhood, North Korea and won't be interested to be left alone without the cooperation of all the world powers. Besides, China has many economic interests which could be harmed if it estranges itself from the civilised world. These interests are much more important than the good relations with a backward country called Iran.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: ANALYSIS / Why is Israel suddenly praising Iran sanctions?