Ferguson criticises Keane in the book for making disparaging remarks about some of his teammates during his playing career at Old Trafford, while ex-United players Ruud van Nistelrooy and David Beckham also come under fire from the Scot.
Keane says he finds it "very strange" that Ferguson has spoken badly of players that helped bring trophies to the club, and consequently contributed to the 71-year-old's success as a coach.
"I do remember having conversations with the manager when I was at the club about loyalty and, in my opinion, I don't think he knows the meaning of the word," Keane told ITV1.
"It doesn't bother me too much what he has to say about me but to constantly criticise other players at the club who brought him a lot of success, I find very strange.
"But I won't be losing any sleep over it."
He added: "I just don't think the manager needs to do it.
"I don't know how many books he's written now but he has to draw the line eventually to say 'listen these players have been all top servants to Man Utd'.
"And a lot of these players helped the manager win lots of trophies so imagine if we'd never won a trophy what he would have said.
"We brought success to the club, we gave it everything we had when we were there.
"But, as I said, it's just part of modern life now, people like to do books and criticise their ex-players."