Ribeiro is keeping the door open regarding a move to Old Trafford after saying Moura is happy for talks with United to continue.
Ribeiro, though, also admitted that the highly-rated midfielder has no problem remaining with Sao Paulo, if the Brazilian club's demands are not met.
"The player is my boss, I always talk to him," Ribeiro told Radio Globo.
"He determines what I do, my objectives. If he says that he doesn't want to leave Sao Paulo, I won't even listen to the offer.
"He told me to keep negotiating when I talked about Manchester United's interest.
"It's a great offer. If it was an irrecusable one, he would leave, but he is happy at Sao Paulo too. If he stays there, life goes on."