United have traditionally been low-key in the winter transfer window in recent seasons.
But Amorim has opened the door to making additions over the New Year, stating: "We want to bring players, everyone here, we want to bring players that we can see a big future in Manchester United.
"We are not just buying one guy because now we feel in December that we need this kind of player for now.
"We want to buy players that we know we are not going to change a lot of times. So that is our idea. I don't know what is going to happen. But of course, we think about how we can improve the team, and in January, the window is open, we can do something."
The manager added, "A lot of things can happen. Even in our club, and you know that we have the World Cup, some players are not playing, they will ask to leave, so I have to manage everything."