"The serious concern of the German government in light of the escalation on the Korean peninsula for which North Korea is responsible was conveyed to him in no uncertain terms in the name of the foreign minister [Guido Westerwelle]," the ministry spokesman told a regular government briefing.
"It was made clear to him that the recent steps toward escalation by North Korean are in no way acceptable for the German government in word or deed."
The spokesman said Germany was consulting closely with "international and European partners" on the crisis and that the subject was certain to figure prominently in a meeting of G8 foreign ministers next week in London.
He said Berlin sought a "decisive and united" response from world powers, after calling on Wednesday for China to play a constructive role in the crisis.
Tensions have soared on the Korean peninsula since December, when the North launched a long-range rocket. In February, it conducted its third nuclear test, drawing fresh UN sanctions.
Pyongyang, incensed at the sanctions and South Korea-US military drills, has issued a series of apocalyptic threats of nuclear war in recent weeks and made a number of bellicose moves that set the region on edge.