The Premier League champions insist the 18-year-old is not ready to make a decision on his international future after notching twice on his first league start for his domestic side.
|14/1||Adnan Januzaj is 14/1 with Paddy Power to represent England
"We gave a clear signal [that we want him to play for Belgium] and now it's up to him. I will respect his choice."
Januzaj's stock has risen after scoring a match-winning double on his first start for United as David Moyes' side came from behind to beat Sunderland 2-1 on Saturday.
The winger is eligible to represent Albania, Turkey, Serbia and Belgium, but United do not want to rush the youngster’s decision.
England is another possibility for Januzaj, with manager Roy Hodgson confirming on the BBC’s 'Match of the Day' programme that talks are lined up regarding the youngster.
"It has to be seriously debated before we start re-nationalising players," Hodgson said. "But there's no doubt he's a real talent and we have our eyes on him. There's a lot still to be discussed."