The midfielder failed to make the bench for Saturday's FA Cup final defeat to Crystal Palace, with Guardiola instead giving Claudio Echeverri his debut as a late substitute at Wembley.
Asked about Grealish's situation, Guardiola says talks will be held between his agent and outgoing sports director Txiki Begiristain and his replacement Hugo Viana.
The manager stated: "We didn't talk - I didn't talk with him.
"People don't believe me, but these things belong to the agents and the club and Txiki, and in this case Hugo as well. Both will decide.
"What is going to happen will happen, but he has to come back to start to play minutes again."
Normal situation
Guardiola insists Grealish's situation isn't unusual.
He also said, "It's not only Jack. There is not one player in my locker room, and I think all the locker rooms around the world, that is happy when they do not play.
"When the team is winning and winning, they have to figure out how everything happens - but they are not happy.
"They are here to play and, when they don't play, they are not satisfied. That is the normal position in all the clubs."