Wigan Athletic manager Uwe Rosler has admitted that he wants to reinforce his attacking department.
There will be no swap deal involving Fernando Torres and Roma's Mattia Destro, according to the Italian player's agent.
There have been suggestions that the Portuguese winger could be on his way out of Old Trafford after failing to command a regular starting place this season.
Arsenal have been linked with the 26-year-old, who is currently sidelined with a hamstring problem, but Ferguson has dashed their hopes.
"We won't be letting him go. We need a Nani," said the Scot.
"His contract isn't up for a year and a half. He offers something different from the other players. He's an incredible talent, the boy.
"Unfortunately, he's injured at the moment. We have sent him over to Dubai for a break, to help him in his recovery.
"He's not far away but he's far enough away. I don't think I will get him until the middle of January.
"He's got a future here. Why would I want to let him go?"