Per Hayters, the City boss was asked about Maresca's nickname and replied: "Diet?!"
His press officer explained: "Like you, but not quite you."
Guardiola laughed and replied: "It's for the hair... it's for the beard."
Guardiola and Maresca have worked together at City, with the latter first coaching the Elite Development Squad and later being appointed to the club's backroom team.
The Catalan added: "I'm really pleased, we spent a special year together but when we were in the second team together, he's an incredible, lovely person, him and his family. He made a really good job, unbelievable, at Leicester, promoting to the Premier League and now being at one of the top five or six teams in England and I wish him all the best because he deserves it. Nice people deserve the best and as a manager, the most important thing to be a manager is to believe something deeply, but deeply, deeply, whatever result, stick with my idea, that's why he believes in what he does and will have success. I don't know how long but he will have it."