The Colombia striker joined United from Monaco in September in a deal that runs until the end of the season, but has failed to nail down a regular spot in Louis van Gaal's starting XI.
Falcao was left out of United's matchday squad for Sunday's 1-0 home defeat to Southampton, but agent Jorge Mendes believes he will find another top club if Van Gaal decides against offering the 28-year-old a permanent deal.
Mendes is widely quoted as saying in the British media: "I don't know [where Falcao's future lies]. He is a fantastic player, and I think it's very difficult for Manchester United fans.
"They have an absolutely brilliant player, one of the very best in the world, who would without any doubt play 90 minutes of the match, every time, with any other club.
"The truth is, right now we don't know what will happen. What we do know is that he will play in one of the very best clubs in the world next season, whether that is Manchester United or not.
"I am 100 per cent sure of that. But you know how football works, we need to wait a little. We'll see what happens."
Falcao has scored three goals in 12 Premier League appearances for United, making seven starts.
