Herrera, who is now at Paris Saint-Germain after moving on a free transfer in the summer, spoke about his five years at United.
While he had good things to say about those around the club, he did feel as though United prioritised things other than football at times.
He told So Foot: "I was very happy at that incredible club. I am very grateful to the supporters.
"Frankly, I was immensely happy in Manchester, but at the club, there were times when I felt that football was not considered the most important thing."
Pressed on whether business was the focus for United, Herrera added: "That does not come out of my mouth.
"I don't know, but football was not the most important thing in Manchester.
"I do not want to compare, all I know is that here, I feel like I'm breathing football on all sides. And I like it."