The 70-year-old has said that he believes the Italian is doing a "great job" at his rivals.
The Scot, who is in his 25th year as manager of Manchester United, has also spoken of his respect for Mancini and has said that he can see him being at the Etihad Stadium for a "considerable length of time".
"I get on very well with Roberto and I think he's done a great job," said Ferguson.
"I respect managers who commit themselves in the way most Premier League managers do.
"He's showing a lot of good decision making – and he's got the strength of character."
Mancini took over as City manager from Mark Hughes in 2009.