The Brazil attacker will join City in January once he finishes the season with Palmeiras.
He told the Guardian: "The presence of Guardiola as manager of City, and the fact that it is a great club, were very important factors in my final decision.
"Guardiola's phone call was a huge part of me deciding to go there. It made me realise that I'd love to work with him.
"I don't know him personally but he made me feel very safe about his project. It was a complicated decision but, in the end, my desire to learn won."