Pogba has endured an indifferent two years at Old Trafford, but the midfielder impressed as France won the World Cup this summer.
Ibrahimovic and Pogba were teammates before the Swede's switch to MLS side Los Angeles Galaxy, and the veteran frontman has tipped Pogba to only improve over the coming years.
The 36-year-old is quoted by Sky Sports News as saying: "I played with him for two years and people like to give their opinion, which they have the right to do. They judge but I think the result speaks for itself.
"You don't need to answer by your mouth, you can answer by your feet, and do what you are good at. That is the way it is supposed to be and the way I like to do it.
"He is young. He won the World Cup, he was in the Champions League final, the Europa League final, the European [Championship] final [with France] - and he won many titles at Juventus. What more is there to say? Just enjoy the games and I know he will become better."
Reports persist that Pogba could potentially leave United before the start of the new season.