The Citizens have re-signed Ilkay Gundogan as a free agent, a year after he left for Barcelona.
Speaking about the situation, Guardiola said there was no hesitation when the chance to sign Gundogan appeared.
“It was a complete surprise and unexpected. It happened,” said the manager to reporters.
“We know him quite well, me personally but the players and the staff and everyone.
“We know the quality he played with last season in Barcelona. He played at a high level, consistency with a lot of minutes, producing a lot.
“We didn’t have any doubts when the possibility was open so we’re absolutely delighted that he’s back.
“I got a message from Txiki (Begiristain) saying Ilkay wants to talk to you. He called me and asked about the situation and if there was a chance to come back if I would like it and we said yes immediately.
“I have a feeling that he doesn’t come here to retire or remember good memories that we have. We have time for the good memories in the future but now it’s time for shoes on and play your best.”