Costa, 28, has been informed by Conte that he has no future at the club and having been frozen out of the first-team squad, the Brazil-born Spain international has gone home to Brazil.
He says Chelsea “want to sell me to China”, but has reiterated his desire to return to former club Atletico Madrid, who are under a transfer ban until January.
“I am waiting for Chelsea to set me free. I didn’t want to leave. I was happy. When the manager does not want you, you have to go,” Costa said in an interview published in Monday’s Daily Mail.
“In January, things happened with the coach. I was on the brink of renewing my contract and they put the brakes on it. I suspect the manager was behind it. He asked for that to happen.
“They gave me a week extra off, but since then it’s fines all the way. They want me training with the reserves. I am not going to do that. I am not a criminal and I am not in the wrong here.
“So, if they need to fine me, let them fine me.”
Costa was particularly scathing in his criticism of Conte, who led Chelsea to the Premier League title in his first season at Stamford Bridge.
“I respect him as a great coach. He has done a good job and I can see that. But as a person — no,” said Costa, who was speaking in his hometown of Lagarto in northeastern Brazil.
“He is not a coach who is very close with his players. He is very distant. He doesn’t possess charisma.”
Faced with Atletico’s inability to recruit players, Costa said he would rather spend a year not playing than join another club.
“My desire is to go to Atletico,” he said. “I have rejected other offers. They want to sell me to China or other teams. If I’m off, I’m going to the club I want to go to, not the club that’s paying the most.
“I am open to being a year in Brazil without playing, even if Chelsea fine me for a year and don’t pay me. I’ll come back stronger. If I was in the wrong, I’d go back now and do as they say.”
Chelsea opened their title defence in disastrous fashion on Saturday, losing 3-2 at home to Burnley, with Costa’s replacement Alvaro Morata coming off the bench to score.
Download our app and read this and other great stories on the move. Available for Android and iOS.