England winger Sterling is the leading scorer across all competitions for City this season, with his 10th of the campaign rounding off a stunning 4-2 win at Napoli in the Champions League on Wednesday.
Speculation in August had suggested the 22-year-old was set to be the makeweight in a deal to bring Arsenal star Sanchez - who has two goals this season - to City before the transfer window closed.
"The transfer window is closed, so it's not time to talk about that," he said. "I have respect for Arsenal and especially for my own players.
"On Alexis, you know my opinion, but he's an Arsenal player - so it's not correct to talk about that – especially before we play them.
"He is an Arsenal player. We have to analyse how to control him because he is such an important player for them, the huge talent that he has."
Guardiola was more forthcoming on the in-form Sterling, who he revealed is reaping the benefits from extra finishing work on the training ground with City coach and former Arsenal midfielder Mikel Arteta.
"I think he is enjoying scoring goals, he's not scared," he said. "Now he realises, wow, how fun and good it is to score goals. Now he is more focused on that.
"Mikel Arteta is working many, many days after training sessions for the last action, for the control in the last moment. For his improvement, [Sterling] wants to stay there and shoot and improve with the goalkeepers.
"He knows the striker has to score goals if you want to achieve the next step. You will not survive in the high-level teams as a striker or a winger if you don't score goals.
"All the strikers and wingers have seven goals or more, it's not just Gabriel [Jesus]and Sergio [Aguero]. That is so important for us."
Guardiola conceded Sterling still has work to do when it comes to the quality of his last pass, with only a pair of Premier League assists to his name this season.
Arsenal's expert in that regard is Mesut Ozil – a player Guardiola knows well from Clasico showdowns against Real Madrid.
"I don't have doubts about him," he added, addressing the torrent of criticism from pundits the Germany playmaker is regularly subjected to.
"First, in terms of quality. I enjoyed him and suffered him at the same time when he was at Madrid.
"Always he is criticised when the team lose. Always, the big men and the big targets are criticised.
"I admire him a lot. Maybe his body language doesn't help him too much but sometimes body language confuses the opinion of the critics and the media opinion of old players."
Guardiola added: "I accept all of you [journalists], your opinions, but old players criticise new players now when a month ago, a year ago they were on the pitch and they know how tough it is working there.
"Old players now who are prestigious journalists forget immediately they were there and they made performances like all the players do right now. It is what it is, we have to accept that. Believe me, I do not understand it.
"I don't have doubts about the quality of Ozil. I think it is good for the Premier League to have player with these talents and hopefully tomorrow he can play a bad, bad, bad game."