Leaked footage has shown Song revealing how Onana cried and refused to talk to him before he was sent home from their World Cup camp.
Song and Onana were involved in a 'blazing row' during their time in Qatar as they reportedly clashed over goalkeeping styles - with the coach unhappy with his No 1 taking too many risks with his feet.
"The day of the game with Serbia I told Onana that I needed to talk to him and he started crying," Song said in the video.
"I told him, 'I don't have time to discuss these issues. I called you yesterday and you didn't talk to me. I had chats with Aboubakar, Choupo-Moting and Anguissa, who are the most representative players in the team; why shouldn't I talk to you?'
"Onana puts on a show in training but takes too many risks during games. I told him repeatedly, 'You should take no risks. Pass the ball wide, not in the middle'.
"He told me, 'I am playing, I don't have time to talk to you'. When he was at the hotel, he didn't talk to me, but went to President Samuel [Eto'o] and he sent him I don't know where."
Song later said his decision to send him home was "for the team's good, given that his honour [in] Cameroon had been broken".