Guardiola says contact has been made but the two clubs differ in their valuation of the Germany international, with Schalke reportedly seeking Â£45million.
Sane, 20, has indicated a desire to leave Schalke but has been linked with Bayern Munich and Real Madrid as well as City.
Speaking at a press conference after City's pre-season friendly at Bayern on Wednesday, Guardiola said: "Sane is a player of Schalke
Of course we talk to him - Schalke know we are interested but at this moment we don't have many possibilities to get him."
Guardiola added, according to City's official website: "There's a difference between City and Schalke and it's quite big but I don't know what's going to happen in the coming weeks and months."
Guardiola has already overseen three signings since taking charge this summer, in Ilkay Gundogan, Oleksandr Zinchenko and Nolito.
City are now travelling to China for the next leg of their pre-season preparations, and face games against Manchester United in Beijing and Borussia Dortmund in Shenzhen.
Source : PA