Guardiola underwent an emergency back surgery prior to the international break and missed City's last two Premier League games as a result.
Guardiola had been feeling severe pain at his back for some time and decided to get it sorted out as soon as possible.
In Guardiola's absence, assistant Juanma Lillo stepped in and led Manchester City to two victories against Sheffield United and Fulham to preserve the champions' unbeaten start to the season.
Manchester City hold the only 100 percent record remaining in the top flight after four games.
A short statement on the City website read: "The manager returned to the City Football Academy this week following his recovery from a routine back operation in Spain last month.
"Guardiola’s assistant Juanma Lillo oversaw the managerial duties for our 2-1 and 5-1 wins over Sheffield United and Fulham respectively prior to the international break.
"Now, the squad turns their attention to our trip to London on Saturday 16 September when we face West Ham United."
After the West Ham game, Man City start the defence of their UEFA Champions League trophy at home to Red Star Belgrade on Tuesday.
