The Football Association (FA) hit Fellaini with a three-match ban for aiming an elbow at his opponent during last weekend's 1-1 draw at Old Trafford in the Premier League, having become angered by Huth grabbing his hair.
Fellaini accepted a charge of violent conduct, meaning he will miss three matches but will be back in time for the FA Cup final against Crystal Palace.
Van Gaal confirmed United will not challenge the ruling. However, the Dutchman believes the FA's decision to also hand a three-match suspension to Huth is an admission United should have been awarded a penalty for the incident.
"We have not appealed because, like I said already, the reaction of Fellaini is like a human being," he told reporters ahead of Saturday's contest against struggling Norwich City.
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"When the FA gives Huth a suspension of three matches then they admit it was a penalty, I have said that also after the match.
"For us it is very disappointing that the referee was not seeing that fact. I think, I still believe that Fellaini makes a reaction like a human being but he has to control himself, that is true.
"But when you grab somebody by his hair, always this situation shall exist."