Toni Kroos' first-half penalty had put the visitors in control in Paris, only for Griezmann's second-half brace to turn things around and put the 2014 World Cup winners on the brink of relegation from the inaugural edition of the Nations League.
"It was a tough first half. We were knocked off our stride a bit by them playing three at the back," Griezmann told UEFA's official website after the game.
"We had to talk and change two or three things tactically. After that it improved.'
"We had a quiet word among ourselves at half-time. We became world champions by working hard for each other."
France boss Didier Deschamps had similar observations, saying 'Les Bleus' struggled to cope with Germany's intense approach in the opening 45 minutes.
"There was a reaction and we upped the intensity and tempo. The Germans played with real intensity in the first half," he explained.
"I modified my tactics after 25-30 minutes and found a better balance that gave more freedom to my forwards, especially Kylian (Mbappe) and Antoine (Griezmann) on the wings.
"It's a good thing in terms of our aim of finishing top of the group, but we were up against a very good German side today."