De Bruyne has shone for City since joining in 2015, but he originally struggled in England having spent a spell with Chelsea.
The Belgian joined Chelsea in January 2012, spending half a season on loan at Genk.
De Bruyne remained in Germany that summer, penning a season-long loan deal with Werder Bremen.
And after impressing for the Bundesliga team, De Bruyne has revealed that then-Borussia Dortmund boss Klopp was interested in signing him. But Mourinho said no.
“When I was at Chelsea, there was so much in the press about my relationship with Jose Mourinho,” De Bruyne wrote for The Players’ Tribune.
“But the truth is that I only ever spoke to him twice. The plan was always for me to go on loan for a bit.
“So I went to Werder Bremen in 2012, and that season went great.
“When I came back to Chelsea the next summer, a few German clubs wanted to sign me.
“Klopp wanted me to come to Borussia Dortmund, and they played the kind of football that I enjoy. So I thought maybe Chelsea would let me go.
“But then Mourinho texted me, ‘You are staying. I want you to be part of this team.’”
But De Bruyne couldn’t force his way into Mourinho’s long-term plans.
He added: “When I arrived for preseason, the vibe was good.
“I started two of the first four games of the season, and I thought I played O.K. Not brilliant, but pretty good.
“After the fourth game, that was it. I was on the bench, and I never really got a chance again.
“I didn’t get an explanation. I was just out of favour for some reason.”
De Bruyne is now battling against Klopp in a race for the Premier League title.
Klopp’s Liverpool are two points ahead of City, though the reigning champions do have a game in hand.