"Look, I had the opportunity at Christmas to do it when Malky [Mackay] left," Bellamy told BT Sport. "They offered it to me then; whether it was part-time I didn't really give them a chance to get into so much of a conversation.
"It was that simple, I'm not right for the club at this present moment. They need to go in a different direction and the club's not right for me at this present moment."
Cardiff are currently 17th in the Championship table.