"Possible misunderstandings should be resolved through dialogue, not through threats," a spokeswoman for the foreign ministry in Berlin said late on Sunday.
Defence Secretary Gotabaya Rajapakse told the Sunday Island that there would be "dire consequences" for any foreign non-governmental organisation, diplomat or correspondent attempting to give "terrorists a second breath of life."
Rajapakse is leading the government's crackdown against the Tamil Tigers who lost their mini state last month in the face of a military offensive that has pushed the rebels back to a narrow strip of land.
"Rajapakse did not mince his words when he said that some ambassadors, especially the German and Swiss ambassadors, and some news agencies were behaving irresponsibly," the newspaper said.
German ambassador Jurgen Weerth was recently summoned by the foreign ministry over remarks he made at the funeral of a newspaper editor and outspoken government critic who was killed by unidentified gunmen.