"It cannot go on like this any longer. We need a stop sign while it is still not too late," Gernot Erler told Passauer Neue Zeitung.
He defended German Foreign Minister Frank-Walter Steinmeier who earlier in June blamed NATO member states for saber rattling, provoking much criticism from German politicians, including those from the ruling Christian Democratic Union.
"Protests show that he hit the mark," Erler said.
Since 2014, NATO has been building up its military presence in Europe, particularly in Eastern European countries bordering Russia, using Moscow's alleged interference in Ukraine as a pretext for the move. Moscow has repeatedly denied the claims and warned NATO that the military buildup on Russia’s borders is provocative.
The bloc's members are set to discuss the Alliance's increasing activities on its eastern flank on July 8-9 at the 2016 NATO Summit in Warsaw.