Wilmots has not promised the flexible teenager he will be going to the World Cup, although the Belgium coach conceded his chances had improved following the news that Aston Villa forward Christian Benteke will miss the tournament in Brazil because of a torn Achilles tendon.
"Things were clear between us: he has received no assurance from me of a place in the World Cup squad," Wilmots added.
"I only said he was selectable. Adnan and his entourage were very receptive and understood the message perfectly.
"The truth will come out on the pitch and he will have to win his place like everyone else.
"What is for sure is that the boy is an interesting player in the absence of Christian Benteke.
"Not many people know but in the Manchester United reserve team, he has often played as a number nine. His versatility is an asset."
The Football Association was keen to get Januzaj to commit to England, even though the player would have had to wait until 2018 to pull on the Three Lions due to residency rules.
But Januzaj, who has Kosovar-Albanian parents, instead chose to represent the country of his birth following a meeting with Wilmots.
"With Adnan and his father, we spoke for a bit more than three hours," the Belgium coach revealed.
"I explained to them both that I know well the sensitivity for a family in Belgium who retain links to their country of origin. I told them whatever Adnan decided would be respected.
"Adnan was born in Brussels, went to school here and his education as a young footballer came at Brussels and Anderlecht before he headed overseas."