The former PM was quoted as telling CNN Portugal that the German government had initially believed it would be better for Ukraine to “fold” quickly against Putin’s onslaught even if it were a “disaster”.
The network reported that Mr Johnson claimed Germany had "all sorts of sound economic reasons" for that stance.
However, German government spokesperson Steffen Hebestreit said that he was “tempted to switch to English and say it’s ‘utter nonsense’ what Boris Johnson said”.
He added: "We know that the very entertaining former prime minister always has his own relationship with the truth.”
He pointed to German Chancellor Olaf Scholz’s strong defence of Ukraine in a speech to the German parliament on February 27, three days after the war started.
“As such, I think the facts speak against the insinuation I heard in this interview," Mr Hebestreit said.
The German government has previously been criticised, including by some within Chancellor Scholz’s own party, over its Ukraine policy, with critics accusing him of timidity and procrastination.
In the interview, Mr Johnson also claimed that the French were initially “in denial” over the prospect of Russia invading Ukraine in February.
“Be in no doubt that the French were in denial right up until the last moment,” he said.
However he stressed that EU nations were now united in providing support for Ukraine. ‘
France’s Emmanuel Macron had attempted a failed last-ditch effort to dissuade Vladimir Putin from invading Ukraine, visiting him in the Kremlin just weeks before the invasion.
The chief of French military intelligence, General Eric Vidaud, was fired in March, reportedly in part due to his failure to predict the Russian invasion, in contrast to the US, which correctly believed a large-scale invasion was likely.