The Spaniard came under scrutiny when he hit back at the Blues' fans for not backing the team, and suggested that he was unhappy being named interim manager when he replaced Roberto Di Matteo in November.
"I'm not going to kick anyone when they're lying down," Ferguson said in a press conference. "It's not my style. My concern is the manager of Manchester United and what happens at Chelsea does not affect me."
United take on the Blues in the FA Cup quarter-final this Sunday.