The Brazil worldwide was assessed on Tuesday and City said Gabriel Jesus has "suffered a fractured metatarsal".
The claim was also backed up by SporTV, and the story is obviously widespread in Brazil given Gabriel Jesus' rising profile.
Guardiola, however, admits that he is unsure whether the 19-year-old will recover before the final league game against Watford on May 21. "Last night he had an operation, it was good, really good".
"Now to be calm, all our support to him and his family and waiting for when he is coming back".
With the injury suffered to Gabriel Jesus, Shaka Hislop and Ross Dyer discuss how Sergio Aguero will fit back into the starting XI.
City take on Huddersfield Town in the FA Cup fifth round on Saturday.
Despite establishing himself as one of the world's finest centre forwards in recent seasons, the Argentine was quickly dropped when Jesus joined City from Palmeiras midway through the season.
"I don't have doubts about Sergio Aguero".
The severity of the injury was reported by the former Betis and Brazilian national team player Denilson, who spoke to Radio Bandeirantes this morning. Sergio was more than professional.