The 18-year old Ivorian midfielder joined Pompey in late October and is now back with City after making three Championship appearances.
"Abdul came on at Watford and did everything I would expect a midfield player to do, so it's disappointing that he has gone back," he told the club's official website.
"He's a talent that I would have liked to have worked with for longer to get the best out of him, particularly playing higher up the pitch because he can pick a pass out.
"But I don't blame Manchester City for wanting him back because they've got some big games coming up.
"If he gets utilised up there, that's fantastic. But if he doesn't play that many games the door here will not be shut, especially for one with the talent he has."