United had been attempting to lure the Sao Paulo midfielder to the club, with the player currently in England with Brazil's Olympic squad.
But Sao Paulo are understood to be demanding around £30 million for the star, and according to Ribeiro, the asking price is simply too high.
"They have reached their limit," Ribeiro told UOL.
"Lucas Moura won't leave. He is happy at Sao Paulo. We have to forget this subject. There is no possibility he leaves now.
"Manchester United made an offer, which was rejected and they won't make another one as they have reached their limit."