Joachim Low has criticised Germany fans who booed Ilkay Gundogan during Friday's 2-1 World Cup warm-up victory over Saudi Arabia.
The Manchester City midfielder caused controversy last month along with Arsenal playmaker Mesut Ozil, by meeting Turkey president Recep Tayyip Erdogan and handing over a Man City shirt signed to "my president".
Gundogan and Ozil, who are both German internationals born in Gelsenkirchen and of Turkish origin, met Erdogan in London alongside Everton striker Cenk Tosun.
Erdogan is in the middle of campaigning after he declared snap elections last month and the German Football Association (DFB) said the players had "let themselves be exploited".
"The fact that a national player is booed like that helps nobody," Loew told broadcaster ARD. "What should Ilkay do now?
"He took a picture, okay, but he has addressed it with the press and underlined his support for German values. The topic has to be ticked off."