Guardiola made his first public comments since an independent commission found City guilty of serious financial breaches between the 2009/10 and 2017/18 seasons.
Posting on X, the former City manager addressed supporters directly, writing: "I want every single Manchester City fan across the world to know I am here; more than ever.
"I am, always have been, always will, be behind my club, my owner, my chairman, Ferran, the players, staff, Enzo and you, our unique supporters.
"Let me be clear: we will get through this together. I love you all."
Guardiola accompanied the message with images from his time at City, including photographs with chairman Khaldoon Al Mubarak, the club's 2023 Champions League triumph and Premier League celebrations.
The Spaniard left City in the summer after a decade in charge, having overseen one of the most successful periods in the club's history. His side won six Premier League titles, three FA Cups and the Champions League, among 20 trophies claimed during his tenure.
The independent commission's findings relate to a nine-season period that largely preceded Guardiola's arrival but overlapped with the early part of his reign.
City were found guilty of arranging what the commission described as "sham" contracts with commercial partners, with the scheme allegedly disguising more than 830 million pounds in funding and artificially inflating the club's revenues.
The club continues to deny the breaches and has strongly rejected the commission's findings. City have confirmed their intention to appeal, with the Premier League setting Friday, October 2 as the deadline.
The verdict leaves City facing the possibility of significant sporting sanctions if it ultimately stands, with a points deduction or expulsion from the Premier League among the potential consequences being discussed.
City chief executive Ferran Soriano has also defended the club, while supporters' group The Citizens Trust said it was reviewing the commission's findings and preparing to consult its membership and wider fanbase.
Guardiola's message comes after his emotional departure from City earlier this year, when he told supporters there was no specific reason for his decision to leave but that, "deep inside, I know it's my time".
Despite ending his time in the dugout, his latest statement made clear that his connection with the club remains intact as City begins the next stage of its fight against the verdict.
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