The former midfielder will leave the Catalans at the end of the season, with assistant boss Tito Vilanova waiting in the wings as his replacement.
However, Rosell admits he was taken aback by the fans' display of affection towards Guardiola in the aftermath of the victory over their city rivals, and insists the door will always remain open for the trainer.
"No one left before the end of the game," Rosell said after the match. "Camp Nou has said tonight loud and clear: 'We love you, Pep'.
"Pep can return when he wants."