The Samba nation are playing against Switzerland this week and as the squad assembled in Basel, one of the main talking points was Luiz's future.
Chelsea rejected a bid from for the 26-year-old last week, but reports from Spain claim a second offer is imminent.
"I will only talk about the national team because this is all I can think about when I come here, that's how I think," Luiz is quoted by Globo Esporte.
"It was like this in Brazil during the Confederations Cup, and it will be like this here.
"You (press) can try everything, but you won't get anything from me."
Meanwhile, Luiz's international colleague and potential Barcelona team-mate Dani Alves was more open on the subject.
"I would be happy if David Luiz would come to Barcelona. I always want the best for my friends and advise them to join Barca if they get the chance," Alves told El Mundo Deportivo.
"He's not just a friend, but he has a lot of quality, too. The problem is not whether he would like to come here, but that you have to take him away from Mourinho and that will not be easy.
"Letting David Luiz join Barca will not be an option for him and even less so as it would make us stronger. It will be incredibly difficult, nearly impossible."