Ralf Rangnick has told Marcus Rashford to forget about the prospect of leaving Manchester United until at least the summer and instead focus on helping the club have a successful end to the season by rediscovering his best form.

Rashford has been linked with a move away from Old Trafford in the aftermath of the 4-1 derby defeat to Manchester City. The 24-year-old watched from the game from bench until the second half despite United missing both Cristiano Ronaldo and Edinson Cavani -- both of whom will be back for Saturday's match against Tottenham Hotspur.

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Interim United manager Rangnick said he has spoken to Rashford since and insists he is "happy," but also reminded the England forward it is not the time for transfer talk.

"I spoke with him yesterday [Thursday] and the day before yesterday, so I don't know anything about that [wanting to leave]," Rangnick told a news conference on Friday.

"He didn't say anything to me, he said to me that he is still happy and that he wants to perform on a high level for the club. There was no mention of him not being happy here.

"The window is closed right now. Even suppose he and his agents or his family at one stage of the summer think about maybe going to another club, well then he can do that but in the summer. Now the window is closed.

"It's got nothing to do with tomorrow's game or the game on Tuesday."

Rashford has suffered a dip in form and was left on the bench at the Etihad as Rangnick chose to face Pep Guardiola's side without a recognised striker in the team.

United's No.10 is without a goal since Jan. 22 and has only found the net twice this year, but Rangnick insists he will remain a central figure in the team while he is in charge.

"I like Marcus as a player," said the German. "I've had a few in the past in former clubs where they had problems at one stage but it's our job to help him, to get the best Marcus Rashford that he can be.

"This is my job right now and I'm putting all my energy and time into that to achieve that."

Meanwhile, Brazil international Fred, weighed in on Rangnick's interim status at United as the club goes about deciding who will be manager for the 2022-23 campaign.

"It's bad because we can't build something with the long term in mind, it has to be short term," Fred said. "There are only a few games left in the Premier League, I hope we reach the Champions League final, but at the moment we have to think in the short term. Let's wait for the summer window, and before the season start, we can build a project for Manchester United.

"Manchester City, for example, didn't become the force they are in the blink of an eye. Neither was [Sir Alex] Ferguson's winning United built overnight. He did it little by little.

"At the moment we have to think in the short term, but from next season on we have to think in the long term, build a solid project and win titles again. That's what we want."