De Bruyne has been heavily linked with a summer move to Saudi Arabia.
He has one-year left on his Blues contract and said last month he would have to consider an offer from the Saudi Pro-League because of the “incredible money” available.
However, Guardiola is unconcerned.
“Kevin isn’t leaving,” he told reporters before his side’s opening pre-season game against Celtic in Chapel Hill, North Carolina, on Wednesday (00:30 BST).
De Bruyne helped inspire City to the Premier League title last season, the club’s fourth in a row and his sixth in total at the club.
Crystal Palace’s England Euro 2024 squad member Eberechi Eze has been linked with a move to City, while Brazil goalkeeper Ederson has also been the subject of interest from Saudi Arabia.
But Guardiola feels it is more likely he will have the same squad as last season.
“If someone leaves, we are going to talk about that and, of course, until the last day [of the transfer window] we have chances,” he said.
“I don’t rule out new players as an option, but I think there is an 85, 90, 95% chance we will have the same squad.”
City begin their Premier League title defence at Chelsea on 18 August.
