City are believed to be preparing to make a move to sign Messi during the winter window.
They tried to bring him in during the summer, but were unable to do so due to the finances involved.
Messi tried to exercise an exit clause in his contract allowing him to leave for free, but La Liga officials intervened and Barca president Josep Bartomeu refused to let him go.
Instead, he was forced to stay put, and was unable to depart for City.
He is out of contract next summer, allowing him to sign a pre-contract agreement during the upcoming January window in order to move to the Etihad next summer.
The player himself is said to be eager on a reunion with Guardiola, and that speculation ramped up again when the Spanish boss signed a new two-year contract this week.
He is now under contract until 2023, and Messi is more likely to cut ties with Barca to move to the Premier League as a result of Guardiola extending his stay in Manchester.
And City are reportedly eager to snatch him away from the Catalan giants as quickly as possible, with suggestions they could work out a deal to see him move in January with Eric Garcia going the other way.
But speaking on Friday, Guardiola appeared to throw cold water over those suggestions, as he insisted he would be happy to see Messi finish his career at Barca.
He said: “Lionel Messi is a Barcelona player.
“If you want my opinion, as a person, I have huge gratitude for Barcelona and what they have done for me.
“In the academy, as a player and a manager, they gave me absolutely everything.
“Right now he is a Barcelona player and the transfer market is in June and July.
“We have incredible games and targets and things we would like to achieve.
“That is the only thing in our mind.
“The rest I cannot say anything.”