Germany midfielder Mario Goetze caused a stir ahead of their World Cup qualifier against Ireland on Friday after briefly donning his own sponsor's socks instead of those of the team's official supplier.
"There is the free choice for shoes here with us, so such actions should not happen," said Germany team manager Oliver Bierhoff. "It is annoying."
Adidas has sponsored the German national team for decades and Goetze has a personal deal with Nike.
The Bayern Munich midfielder told Bild newspaper he was not trying to advertise his sponsor but wore the socks before training on Thursday as part of his recovery from injury.
"These are compression socks which I have been wearing due to my injury,' said the midfielder, who has only recently returned to action after hurting his ankle in August.
"I did not want to provoke or advertise anything. This will not happen again," said Goetze, who joined Bayern this season for 37 million euros.
Goetze was fined by Bayern after appearing at his official presentation with a T-shirt sporting a large Nike logo. Adidas, which holds shares in the German treble winners, is the club's official kit supplier.