Herrera was a regular in the United side before the surprise news that he would be leaving at the end of the 2018/2019 as a free agent.
The Spaniard, who was a fan favourite, made 189 appearances for the Red Devils in five years and helped the club lift the UEFA Europa League, League Cup and FA Cup.
Herrera felt that he deserved to be treated by the club after they took too long with his contract offer.
"It was not about money. It was not about the duration of the contract offer," Herrera told The Athletic. "In my opinion, I waited too long (for an offer) and deserved more attention from the club.
"I was a player that gave everything. I never complained. I never went to the media to complain about anything.
"I never put a bad face to any manager, to any member of the board, and they waited until I had five or six months left on my contract.
"That's why I had some disagreements with them. I tell you this but I also tell you that it is part of football, part of life, nothing personal at all - but you ask the question and I give my point of view, as a professional player."