Can I (as an Iranian) apply for a Chinese visa in China embassy in Malaysia?

You can apply for it but I am not sure you will succeed. There are extra requirements for non-Malaysian applicants. You have to prepare a copy of your passport information page together with the original and a copy of the Malaysia visa with the original. If you stay in Malaysia for short-term, a copy of declaration letter should be provided. From March 4, a new policy will be implemented. Both Malaysian citizens and Non-Malaysian citizens, should provide documents about travel to China, such as round-trip airline ticket, proof of accommodation and so on.