File Photo: Walker, Guardiola. AFP
Walker started as a substitute in the Champions League final when City completed a historic treble last month, and the German champions are keen to bring him to Munich.
But ahead of City's clash against Bayern in Tokyo on Wednesday, Guardiola insisted the 33-year-old was "an incredibly important player for us".
Walker has "very specific qualities that are so difficult to find worldwide. I know we are in touch, both clubs," Guardiola told reporters.
"We will fight for him, like I'm pretty sure Bayern (will). I don't know how it is going to finish."
Guardiola was bullish when asked if Walker would be considered for selection against Bayern, saying "of course, he's our player".
"We need the best players," he said.
"He's our player and we hope he's going to stay all the season with us, so why should he not play?"
Another Premier League player on Bayern's radar is Tottenham Hotspur striker Harry Kane.
The German champions are said to be intent on securing the signing of England's record scorer, whose contract with Spurs runs out in 2024.
Kane's camp is believed to have approved the move, but Bayern need an agreement on a transfer fee with Tottenham to seal the deal.
Bayern technical director Marco Neppe and CEO Jan-Christian Dreesen remained in Europe rather than joining the team on their trip to Asia.
Bayern coach Thomas Tuchel opted for an enigmatic response when asked why, merely saying they were "doing something that is necessary for them to do in Munich to support us".
Guardiola said of Kane that he didn't "have words to say how good he is," but was similarly hesitant to be drawn on the subject of his potential move to Bayern.
"He is a Tottenham Hotspur player. I understand Bayern always wants to take the best players in the world, so Harry Kane is one of them," he said.
"I cannot say anymore. He is not our player. I can talk about Kyle, but Harry Kane is not my business so I'm sorry."
City won the first game of their Asian tour 5-3 against J-League Champions Yokohama F-Marinos on Sunday.
After playing Bayern in Tokyo on Wednesday they will travel to Seoul to take on Atletico Madrid.
After facing City, Bayern will take on J-League side Kawasaki Frontale in Tokyo on Saturday, before travelling to Singapore for a game against Liverpool.
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