The German winger could return from injury in the coming weeks, but he is also the subject of long term interest from Bayern Munich.
While it would take a huge fee to tempt City to sell midseason, their manager is not sure when Sane will be ready to join the first team.
Sane did want to leave City in the summer before he suffered a knee injury in August.
"When will he be back? I don't know," Guardiola told a news conference ahead of City's Carabao Cup trip to Oxford United on Wednesday.
"The process is [about] getting perfect, not setbacks.
"I think he is physically strong, muscular, but he is recovering well. The next step is on the pitch and then the team, and always will be so happy when he is back."
Asked about a possible move in January, Guardiola said: "I don't know about that. Anything can happen."