The England forward has been heavily associated with a proceed to Manchester United but City were also thought to be a potential destination for the Londoner.
Sancho made a decision to leave the Premier League side for Dortmund three years ago amid a lack of first-team opportunities at the Etihad, with the winger having since flourished into arguably the most exciting young talent in world football at present.
It was announced on Tuesday that the Citizens' winger Leroy Sané is moving to Bayern Munich and this refuelled speculation that United's rivals would scupper their move for Sancho as he is an obvious like-for-like replacement for the German.
"When he chose to move to Dortmund it's not because he is going to decide to come back one year later".
Asked whether he will need to rebuild, Guardiola said: "Not for the lack of quality but the absence of Vinny, David".
"When he chose to move to Dortmund it's not that he's going to come back".
"It happens in other clubs and when players decide to leave, Jadon Sancho and Leroy - especially Leroy". It would make no sense. "If he wanted to leave then, I'd say he doesn't want to come back".
After winning the Premier League for the past two years and a domestic treble last season, City have handed over the title to Liverpool this term.
Guardiola accepts that he will have to make changes in his squad with a centre-back a priority after the failure to replace Vincent Kompany when he left last summer.
Guardiola mentioned: "It's section of the process".
"But it's not a disaster thing, or bad thing, it's part of football for the age, for the normal situation and circumstances".