US Ambassador John B. Emerson was called in "in connection with an investigation by the federal prosecutor," the German Foreign Ministry said in a statement.
The US envoy "was asked to help in the swift clarification" of the case, it added.
Federal prosecutors say a 31-year-old German man was arrested on Wednesday on suspicion of spying for foreign intelligence services. They did not identify the suspect or the intelligence services.
German government spokesman Steffen Seibert told reporters that Chancellor Angela Merkel been personally informed of the arrest, AP reported.
He declined to comment on reports by Der Spiegel magazine and the daily Sueddeutsche Zeitung that the man worked for Germany's foreign intelligence service, known by its German acronym BND.
The newspapers said the man was suspected of passing on information about a German parliamentary committee investigating the activities of US and other intelligence agencies in Germany. He worked with US intelligence since 2012, they reported.
Seibert said members of the parliamentary panel had also been informed of the arrest.
Reports that the National Security Agency spied on German citizens, including on Merkel's mobile phone, have caused friction between Berlin and Washington since they were first published last year, based on documents leaked by former NSA contractor Edward Snowden.
Martina Renner, a member of the opposition Left Party on the parliamentary panel, said the case indicated that anyone who examined Snowden's revelations in detail was subject to scrutiny by US intelligence agencies.
The US National Security Council declined to comment and BND did not immediately return a call seeking comment.