The 24-year-old was an integral part of Cruzeiro’s side which secured the Campeonato Brasileiro Serie A title this season.
The Under-20 Brazil international had recently expressed his interest in a potential move to the Premier League champions.
But Mattos insisted United have not made an approach for Ribeiro and the Red Devils would need to bid in excess of £6.5m to secure the 24-year-old’s signature.
“There are no offers, just speculation,” Mattos told Globo Esporte. “Everton Ribeiro said he dreams of playing for Manchester United, then people started talking, and they said he would cost €8m – that makes no sense.
“We turned down a €10m offer [from a different club] for the percentage we own and that happened halfway through the season.
“Cruzeiro don’t want to let any player go. On the contrary, we want to bring in more players and that’s not me talking, the president said that. Of course we are responsible, and if an absurd offer for Everton Ribeiro or any other player comes, we have to sell.”
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