Guardiola penned terms to 2023 yesterday to end talk of a return to Barca.
Koeman said: "I am happy with the renewal of Guardiola's contract with City.
"It is important that Pep can work at City because he is important as a coach and he is a reference for all coaches.
"On Thursday I spoke with him to congratulate him and if he is happy I am happy. It's good news that he continues to train at City."