Erik ten Hag has said Manchester United will not sign a striker in January due to financial restrictions.
Speaking in his press conference ahead of United's FA Cup fourth round match against Newport, the Dutchman said: "I looked but there is no space.
"There is no space for FFP to do something about this lack of quantity in the striker position."
Rasmus Hojlund - a £72m summer signing from Atalanta - has scored just twice in the Premier League so far, while Antony Martial has been ruled out until April with a groin injury.
"Of course, [Marcus] Rashford can play as a striker; we have some other alternatives and it's clear that Anthony is out for a couple of months it's a gap in our squad, clear."
Reports in The Sun on Thursday suggested the club had turned down the chance to land Karim Benzema.
The club reportedly refused to enter talks, due to what they claim are "exorbitant" sums involved in bringing the 36-year-old, who earns £86m a year in Saudi Arabia with Al Ittihad, to Old Trafford.
Ten Hag: Klopp departure 'not good' for Premier League
Ten Hag also spoke about the announcement that Jurgen Klopp will leave Liverpool at the end of the season and his impact at Anfield.
"It's not good for the Premier League. He has made an era there. He built the club, he brought the club back I think where they belong, so congratulations on that," the Dutchman said.
"He has done an amazing job in Liverpool."
Ten Hag said he could understand Klopp starting to feel as though his energy was running out, adding: "Nine years is a long time. The Premier League is very intense, in combination with European Cup football."
Follow the January transfer window
The winter transfer window is open and will close at 11pm in England and 11.30pm in Scotland on Thursday February 1.
To ensure harmonisation with the major leagues in Europe, the closing dates were set following discussions with the EFL, DFL, Serie A, LaLiga, and LFP, who will all close their summer and winter windows on 1 September and 1 February respectively.
Keep up to date with all the latest transfer news and rumours in our dedicated Transfer Centre blog on Sky Sports' digital platforms, while you can also catch up with the ins, outs and analysis on Sky Sports News, including daily transfer shows, and listen to our Transfer Talk podcast.