Januzaj was shown a yellow card for simulation after throwing himself to the ground with Collins in close proximity, during a game that the defending champions went on to win 3-1.
The 18-year-old was warned by his manager David Moyes not to let diving "creep into his play" and Collins is confident the Belgian-born youngster will heed that advice.
But he was nontheless decisive in his view of Januzaj's actions.
"It's cheating basically," Collins told Sky Sports News.
"I don't like to see it in the game. He probably thinks I am going to stick my leg out and he's probably already thinking about going over.
"Obviously he's taken a dive. He's a young lad, a great player, I'm sure he will learn.
"David Moyes seems to have this conversation quite a lot at his club with Ashley Young.
"It happens in football. He (Januzaj) is a great player and played very well at the weekend. He's learning the game and if he carries on playing the way he is, he is going to be a top-drawer player."