Kirchhoff has already signed a deal with the Bavarians from July but, given a potential shortage of central defenders, Bayern had been pondering bringing the move forward.
"You never know what might happen tomorrow, but the way things are at the moment it looks like I will be ending the season with Mainz," said Kirchhoff to Sky television.
"I don't know what's happening behind closed doors - that is what agents and managers are for.
"But I am only concerning myself with the task in hand. I am a Mainz player."
The 22-year-old has become Bayern's first signing for next summer and could replace Daniel van Buyten, whose contract with the club is up for renewal in the summer.
With Holger Badstuber out injured until March or April, Van Buyten should be given a chance to stake his claim for a new contract, but the premature arrival of Kirchhoff would intensify the competition for places.