Berlin summoned the US ambassador over eavesdropping
German officials told ambassador Simon McDonald that "the interception of communications from the premises of a diplomatic mission would be an internationally wrongful act", Xinhua quoted the foreign ministry as saying.
No further details of the meeting have so far been made public.
London-based Independent newspaper Tuesday reported that Britain could be operating a "covert listening station" in Berlin using the equipment housed on its embassy's roof.
The report said the equipment could be used to eavesdrop on mobile phone conversations and to supervise the communications in government offices.
The report came as German officials are outraged by allegations that US intelligence may have targetted Chancellor Angela Merkel's mobile phone.
Last week, Berlin had summoned the US ambassador over the eavesdropping allegations.
"We should also make a no-spy agreement with Great Britain," said Wolfgang Bosbach, a German lawmaker from Merkel's party. "It is regrettable that such agreements between partners are necessary at all, but a complete espionage is totally unacceptable," Bosbach added.