Gill rejected allegations that United were trying to intimidate French second division club Le Havre who say Pogba had agreed to join them before signing for the Premier League champions.
Le Havre have said they will take the matter to football's governing body FIFA.
"It's not intimidation but they can't insult us," Gill said.
"We are not intimidating Le Havre, we have no intention of intimidating Le Havre, they can take whatever action they fell appropriate," he said at a meeting of the European Clubs Association.
"We have done everything by the book, we are confident in that, they can take whatever action, we won't be insulted by Le Havre.
"It's an insult by Le Havre to suggest that Manchester United and employees of Manchester United have paid the parents and bought the player's parents a house.
"We will not accept the good name of Manchester United being trawled around Websites and the press saying we have done these things we are not allowed to do.
"If they want to take action, they can take action, we will defend our case in the football bodies, we are very comfortable about doing that."
The allegations first arose last month when Le Havre accused United of offering very large sums to Pogba's parents to end his contract with the French club.
"Manchester United has today written to Le Havre to put it on notice that action will be taken if such allegations are repeated in relation to the transfer of Paul Pogba," United said in a statement.
