The former player of the club believes the Bavarians have no option, but to cough out big money if they need quality in their squad.
After helping the side to their seventh consecutive Bundesliga title, Ribery insists the qualities of Serge Gnabry and Kingsley Coman are not enough to win glories for the side ahead of the new season.
Ribery also thinks the signing of Leroy Sane will be a boost for Bayern Munich.
"Bayern needs quality, you have to invest!" Ribery told Bild. "I am very excited about what they do.
"Only with Serge Gnabry and Kingsley Coman, it is perhaps too little to go into the new season.
"Sane would be a player who brings Bayern forward. Skills, can play on the right and left side, I'm curious to see if he will really decide for Munich and fancy the Bundesliga."
After urging his former side to splash the cash this summer, the 33-year-old joked of a return to the club if they do not find any solution to his departure as he also revealed new offers from European clubs.
"Maybe they [Bayern] call me again if there is no other solution," Ribery joked. "No, seriously: The chapter at Bayern as a player for me has ended fantastically in May.
"There are many good offers from Europe, but I also have to look at the family, my children. If you've been at Bayern for so long and it's your second home, moving away from here is not easy."
Ribery, who joined Bayern Munich from French Ligue 1 side Olympic Marseille in 2007 brought his twelve-year spell with the German giants to an end after the 2018/19 season.
Ribery recorded six goals in twenty-five league games with his seven Champions League appearances yielding a goal.
