Van Gaal felt compelled to defend his tactical approach, even producing a leaflet for the benefit of the media, following criticism from West Ham manager Sam Allardyce, who suggested United "thumped it" in earning a 1-1 Barclays Premier League draw at Upton Park.
"There was no reason (for Van Gaal to defend himself)," said Gunners boss Wenger, speaking ahead of Sunday's FA Cup fifth-round clash with Middlesbrough.
"A big club has a responsibility to win and try to win with style - but first try to win.
"I didn't understand really what the problem was
Man United went a bit longer in the last 10 minutes - I found it completely logical.
"If I am in a game in the last five minutes, we have a free-kick and we have three monsters up front, I do not say 'play a short ball'.
"A team goes naturally from its strong points and an intelligent team knows how to exploit its strong points.
"When we have (Olivier) Giroud on the pitch the players understand quickly that we can play a bit longer, we can cross the ball more, because he will win the ball in the air.
"I don't even think Van Gaal said to them 'go longer'
When they saw (Marouane) Fellaini on the pitch the guy at the back said 'I'll kick it to Fellaini and (Robin) van Persie or (Wayne) Rooney can score the goal'
Giroud replaced Alexis Sanchez in Tuesday night's Premier League defeat of Leicester after the Chile forward suffered a blow to the knee which could yet rule him out of the Middlesbrough clash.
The France striker could play from the start against Manchester City's conquerors as Wenger felt Sanchez showed signs of fatigue in addition to the knock.
"He was not himself," Wenger added.
"I don't know if it was down to the kick he got on his knee
I'm not sure he was free in his head to sprint as he used to before
He had not the same intensity in his game as he had until now."
Wenger played down any prospect of Sanchez joining Arsenal's list of wounded after a recent hamstring problem.
"Muscular (hamstring) now should not be a problem," Wenger said.
"(But) he still has a swollen knee
He cannot move well.
"It's only a kick
It's nothing else
You can move or you cannot move
If he has no problems to move his knee it's no risk.
"If he's not available for Sunday, he will be available next week.
"If there's any medical risk he will not play."
Source : PA