Messi claimed after the game that Van Gaal "disrespected" Argentina in his "pregame comments."
"I knew what Van Gaal had said but it [the goal celebration] happened on the spur of the moment," Messi said in an interview in Paris with Andy Kusnetzoff's "Perros de la Calle."
"I didn't like what I did, I didn't like what happened after. These are moments of nervousness and everything happens very quickly."
The Argentina captain was seen arguing with Van Gaal and his assistant, Edgar Davids, at full-time.
Messi, meanwhile, said despite the long wait to lift the World Cup, he wouldn't have it any other way.
"I think if I had to choose the moment, it would have been this one," Messi said. "It's at the end of my career, closing a circle.
"I achieved everything with the national team as I always dreamed of. I got everything in my career, individually. It was closing my career in a unique way.
"I never imagined that all this was going to happen to me when I started and getting to this moment was the best ... I have no complaints and I can't ask for more.
"We won the Copa America  and the World Cup, there's nothing left."
Messi said he wishes that Diego Maradona could have seen Argentina win the World Cup for the first time since the Napoli legend helped his nation lift the trophy in 1986.
Maradona, who coached Messi at the 2010 World Cup, died in December 2020.
"I would have liked that Diego Maradona would have handed me the [World] Cup or at least to have seen all of this," Messi said.
"To have seen Argentina as world champions, considering how much he desired it and how much he loved the national team. I think he from above, as well as many other people that love me, gave me strength."