"We have our ideas, for some players we are open for loans but with some players they are not, because they are first, talented, they have to develop first in our environment," Ten Hag told reporters.
"Second, we have many games to cover and we need players to cover that. When you play 30 games in 10 days you need a lot of players. The way we put on Pellistri on Wednesday is already a signal."
Pellistri made his first-team debut for the Red Devils against Charlton Athletic on January 10 before featuring for a second time in Wednesday's EFL Cup contest with Nottingham Forest.
However, Ten Hag has revealed that Zidane Iqbal and Brandon Williams could depart before Tuesday's deadline.
Iqbal is yet to feature for the first team this season, while Williams has only played once - five minutes against Burnley in the EFL Cup fourth round on December 21 - since returning from injury.
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Ten Hag reacts to Pellistri's cameo in Nottingham Forest win, reveals if he could play vs Reading
"We have seen some physicality and he [Facundo Pellistri] has some good movements and some good runs in behind," said Erik ten Hag after Man United beat Nottingham Forest 3-0.
"He has speed so he has to bring that in our game. I think he is also a player who can play really good between the lines because he can be ball-secure. That he has to bring into our game.
"[He is] a little bit different, we have a left-footed right-winger in Antony, and Facundo is right-footed and I think a best chance was, well not our best chance, but a good chance he created, was his cross for Wout Weghorst."
When asked if Pellistri could feature against Reading in the FA Cup, Ten Hag added: "After today, I have something in my head but I have to settle this game down and look into my plans and I have to look into Reading and then we have to make a good plan to beat Reading."
Pellistri impressed fans with his 20-minute cameo, playing a key role in the build-up to our third goal.
Giving him a chance against Reading would certainly come as a boost to the youngster, who has hardly featured for the senior team since joining.
