"He just told us to believe," De Bruyne told the Daily Mail.
"He doesn't want us to have doubts in the way that we are playing. He wanted to make sure that we know the way we are playing now is the good way.
"That was the message. There are a lot of risks in how we play, we know that. I know this is not a very patient world but we are trying something very new."
City have seen their lead at the top of the Premier League evaporate and are ahead of Arsenal and Liverpool only on goal difference. They also trail Barcelona by five points in their Champions League group after three games.
Guardiola has made some big decisions since joining City in July, sending goalkeeper Joe Hart out on loan and dropping striker Sergio Aguero for key games.
De Bruyne said the Spaniard has made it clear there was no place at the club for players who cannot adjust to his system.
"You just need to adapt otherwise you won't fit in. And if you don't fit in then you will have to go somewhere else," De Bruyne added.
City face Manchester United in the fourth round of the League Cup on Wednesday before travelling to face West Bromwich Albion in the league three days later.
(Reporting by Shravanth Vijayakumar in Bengaluru; Editing by Peter Rutherford)
