Sean Kearns of Metro reported the French World Cup winner has a bonus clause in his contract that will be activated if he stays at Old Trafford.
The Spanish transfer window is set to close on August 31, leaving United with an anxious wait.
Manchester United manager Jose Mourinho dismissed the player's recent comments after the opening 2-1 win against Leicester City. Pogba was made captain for the game and said he would be punished by United if he gave an honest appraisal of his thoughts.
Per Kearns, the France midfielder said: "There are things I can say and there are things that I cannot say. Otherwise I will get fined."
However, Mourinho has countered Pogba's comments, saying he is delighted with his current contribution at the Theatre of Dreams.
Reporter Mandy Henry quoted the Red Devils coach:
Pogba returned to United in a world-record transfer two years ago, but the player has failed to set the Premier League on fire.
The Frenchman has the physical strength to be a huge success in England, but the technical style of La Liga would appeal to his skill set.
Barca would be a great home for Pogba if he decides to leave United, but he will forever be remembered as a talent who didn't succeed at the club that guided him through his youth.
Pogba has much to prove at Old Trafford, and the 25-year-old has plenty of time to move to the Camp Nou.
Mourinho needs the player to be a catalyst and a leader this season; otherwise United could quickly fall out of the top four.