Leno made the decision in October 2024, when he was selected to be third-choice in Germany's then squad.
"I'm quite relaxed about it now and I'm not putting any pressure on myself. I'll be 34 in March, and I made the decision consciously," Leno told Sport1.
"Everything was very respectful. It's not like there was a war of words or anything disrespectful happened. Julian Nagelsmann also said that no door was closed. Of course, the door didn't open any further."
Leno played nine international matches for Germany, the last in 2021. He was last in the squad in March 2024.
"Of course, I never said I was retiring; there was more media coverage. I made the decision and said that I would concentrate more on Fulham than on traveling with the DFB and then sitting on the bench or in the stands," he concluded.