F1 now heads from Hamilton's home turf at Silverstone to Hockenheim, where German-born Rosberg might expect similar levels of local support.
Not so, Hamilton told reporters, because Germany is "not really his home race" as Rosberg has a Finnish father and he grew up and still lives in Monaco.
"What a stupid and unnecessary attack by Hamilton," said the major German daily Bild.
Also in reaction, Sport Bild published a huge colour photograph of Rosberg's face decorated with painted German flags.
On Facebook, meanwhile, big football fan Rosberg celebrated Germany's 7-1 win over Brazil in the world cup semi-final by posting a photo of himself in a room littered with Germany-themed flags and memorabilia.
And when asked about Hamilton's comments after testing at Silverstone on Tuesday, Rosberg said: "Anyone can judge however they want.
"What do you want me to say?"
He admitted he might not be as German as Hamilton is British "because I didn't grow up in Germany, but I consider myself 100 per cent German."