A video of Madine insulting Sharp emerged on social media before United's game against Bolton Wanderers two years ago, with the on loan striker, then plying his trade in Greater Manchester, later being withdrawn from the fixture.
But, speaking in United's matchday programme ahead of today's game against Queens Park Rangers, Sharp confirmed talk of problems between the pair is wide of the mark.
"It was all fun and games back then," he said. "It was not a major issue at the time.
"Gary apologised through a mutual friend and it was sorted , man to man."
Madine arrived on loan from Cardiff City earlier this week and Sharp added: "He plays for Sheffield United now, he wears the red and white shirt and he's here to help us win promotion."