Gary Neville was critical of United's display in their 2-1 win at Southampton, while Paul Scholes said United were at risk of falling behind rivals Manchester City after the latter opened a £200million academy and training complex.
Van Gaal was unflustered by the pair - who represented United a combined 900 times in the league - and was particularly dismissive of Scholes' claims.
Neville slammed Sunday's clash between United and Liverpool as comparable to a clash between pub sides - "The Dog and Duck versus The Red Lion" - but Van Gaal was not moved on the former captain's assessment.
"I don't know the context, how he [Neville] said that, so I cannot answer that," Van Gaal said, when asked about Neville's criticism.
"I can only say what I have already said; as a legend, or ex-legend, or as a commentator you have to pay attention to your words."
On Scholes, Van Gaal responded: "[He's] also a legend, yeah? Also a legend. He has to pay attention also to his words, I think.
"The building [City's academy] is not so important. The accommodation is not so important. It's the philosophy and the staff is important.
"And then comes, of course, the talent. You have to work with talent.
"I don't have the time to compare the talent and the staff with each other, so I cannot answer that question."
Van Gaal comes up against Brendan Rodgers for the first time, with Liverpool's manager having tipped the Dutchman to struggle in the Premier League in pre-season.
The former Netherlands boss said Rodgers' prediction was apt.
"Yeah I think he said at that moment the truth and I have experienced that way also," Van Gaal conceded.
"Because the big difference between the leagues where I have worked and the Premier League is the high rhythm of the game.
"And I think also every club has in his squad a player who can decide the match, and that was not so like in Germany, or in Spain, or in the Netherlands."
