Reports over the weekend indicated City was interesting in signing Mbappe from Paris Saint-Germain, with Sterling potentially included in the transfer.
The England international is yet to sign a new contract with City, with his deal expiring in 2020, leading to speculation the Premier League champion could cash in.
But Guardiola gave a rebuttal to suggestions City and PSG could set up a swap with World Cup winner Mbappe moving to the Etihad Stadium and Sterling heading to Paris.
"Mbappe is not going to happen," Guardiola said.
"City aren't going to spend the money that Mbappe and PSG deserve.
"PSG are not going to sell him, I guess.
"I don't understand where that news comes from.
"We are not going to swap for Sterling or any other top player we have.
"People should be more respectful to my players, and to players of other teams."
A shock loss at home to Lyon two weeks ago leaves City under pressure ahead of their Champions League tie with Hoffenheim.
City has now lost five of its last six UEFA Champions League games under Guardiola, who won the tournament twice in his time in charge of Barcelona.
And Guardiola is under no illusions about the importance of Tuesday's meeting with the Bundesliga side, coached by 31-year-old Julian Nagelsmann.
"We have five finals ahead in the group stages. Tomorrow is the first final," Guardiola told a news conference, echoing comments by City captain Vincent Kompany.
"Like Vincent said perfectly, it's a top-quality competition, it's so complicated for all of us and we try to be stable. I think we are making steps forward.
"Julian Nagelsmann is so young and Hoffenheim keep getting better and better. He will have a lot of success in his career. I am looking forward to facing him and hopefully it won't be the last time we play each other."