When Barcelona celebrated the league title on the streets of the city, Yamal held a flag from the open-top bus and also posted pictures from the celebration on Instagram.
At a press conference on Tuesday, coach Hansi Flick was asked about Yamal's actions.
"I don't normally like this kind of thing. I've talked to him and said that if he wants to do it, it's his decision. He's 18 and old enough," Flick said.
Around 750,000 people are estimated to have participated in the celebrations in Barcelona.
