Douglas has been linked with a £20million move for the 18-year-old.
United scout, and former star defender, Jaap Stam watched the youngster in action earlier this month.
“Douglas still has to grow up,” Bottega told Terra Brazil.
“I wouldn’t like him to be transferred to a European team yet because when you start to negotiate with teams from the European market like the Italian, English or Spanish, it is not always possible to make your wishes come true and that puts pressure on.
“I think that it is too early to transfer to a team like Manchester United, but if they have offered 80 million Reais (Brazilian currency – £20million) to Gremio then that is important.”
“The Europeans already knew Douglas as they have seen him play in the Brazilian youth national teams but they needed to see him in action for a senior side,” added Bottega.
“Against Santos and Botafogo, Douglas showed that he can play among professional players but that doesn’t mean that he has to be transferred to a European team now.
“We know about the interest of some teams and that the offers are important but I have the same opinion as that of his mother, in that it isn’t the moment yet to be playing in Europe.”