The Canada-born midfielder spent four seasons with United, but made just 27 league appearances due to a number of injuries.
In his new book, My Autobiography, the Scot also admitted that there was "something" about the England international that he did not like.
"When I signed him, there was something about him I didn't like. The thing every good leader should have is an instinct," he wrote.
"Mine said to me: 'I don't fancy this.' When he came over to Old Trafford for the medical, I still had some indefinable doubt. He was very hail-fellow-well-met. Almost too nice."
Hargreaves later joined Manchester City on a free transfer, but made just one league appearance before leaving in 2012.