"I need to download an Instagram account", Guardiola said.
Social media funnyman Benjamin Mendy (also a professional footballer) appeared to have been in hot water with his manager for a short while on Friday.
Guardiola confirmed that Mendy will be unavailable for Sunday's match against Chelsea, adding: "His injury is not easy".
"Wow, I didn't know", Guardiola said, per the Manchester Evening News.
Pep Guardiola was lost for words when he was informed in his press conference on Friday, exclaiming: 'In Hong Kong?
"Before he went he said "I'm going one day to Paris", and that's OK because that's here, but Hong Kong is far away, so I don't know". 'I didn't know. F***!
But Guardiola may not see the amusing side this time - after the 2-0 win against Arsenal in the opening game of the season, he half-jokingly called on Mendy to focus less on social media and more on developing as a player.
Last August, the Manchester City boss expressed his desire to see Mendy put his phone away and concentrate on his football.
Asked why Mendy is in Hong Kong, Guardiola said: "He's in Barcelona". "[It's not okay to be in] Hong Kong, definitely not". Meniscus. It is not easy.
"You can't return and train for two days and then you are fit".
Mendy eventually responded by saying he was just playing a prank and was actually still in Spain.
Pep continued: "Yesterday he was in Barcelona".
Mendy, a notorious prankster on social media, later tweeted to confirm that it was a wind-up and he is still in Barcelona.
Mendy enjoyed a sensational start to the season, supplying five assists in nine Premier League appearances but he has been beset by knee problems for the second season running after missing virtually the entire 2017-18 campaign with an ACL injury. He returned against Burton Albion in the League Cup but suffered a set-back, putting him back on the sideline.