Kimmich opened the scoring for the hosts at the Allianz Arena, but Bayern failed to make the most of a spate of chances after that and were duly punished as goals from Marcelo and Marco Asensio put Madrid in the driving seat ahead of next week's return leg at the Bernabeu.
Bayern must now score at least twice in the Spanish capital to avoid crashing out at the hands of Spanish opposition for the fifth season in a row, but Kimmich believes that his side are still in the tie despite heavily criticising their first-leg display.
"We were completely naive and reckless with our chances. Real shot twice on goal and twice they scored. That's their quality and that just [must] not happen to us," he told reporters.
"If a team shoots twice on goal and scores twice, that's quality. But today they have also clearly shown that they have very big weaknesses. Last season we also turned it around, more or less, so that we took the game into extra time. We know that we have to score two goals. It's possible – Juve showed that, we showed it last year.
"I would say the game itself was not a bad one, but such mistakes are simply punished in the Champions League semi-final, especially against Real Madrid. I did not expect that we would have so many chances, but you just have to take them and kill them in the first half."
Madrid are bidding to become the first team to lift the trophy three years in a row since Bayern themselves achieved the feat between 1974 and 1976.