During the summer transfer window, City made five big-money additions in an attempt to mount a stronger challenge for the Premier League title, but it appears that Guardiola is not finished with reshaping his squad.
According to Don Balon, Guardiola is prepared to meet the release clause of the versatile 25-year-old, which is set at £35.3m.
Barcelona are allegedly keen to keep Roberto at Camp Nou, but the player's wage demands are said to be on a par with star defender Gerard Pique.
The academy graduate has made 150 appearances in all competitions, but has only made 58 starts in La Liga since 2011.
Manchester United have previously been credited with an interest in Roberto, who has just under two years left on his existing deal.