France trailed 4-0 at halftime in the World Cup third-place playoff before mounting a spirited recovery, but their late rally was not enough to prevent Deschamps' 185th and final match in charge from ending in a loss.
"It is a defeat, but we were 4-0 down. We produced an unacceptable first half," Deschamps told reporters.
"There was a reaction, with the things we know how to do well. We had two chances to make it 4-4, but we pushed forward a little more.
"That is what we know how to do, but we didn't do it. It is my fault because I must not have done what was needed in the first half."
Deschamps said the performance after the break at least restored pride, though he admitted the sporting disappointment of France's tournament remained considerable after they had arrived in North America bidding to win a third world title.
"It would have been better to finish third," he said. "We came here with a lot of ambition. We managed to do quite a few positive things.
"We failed in our match against Spain, and they knew how to perform against us. This is a group with footballing quality. There was enough talent to get results," Deschamps added.
"On a human level, it was a beautiful adventure. Eight weeks, it was beautiful."
France's 2-0 semi-final defeat by Spain ended their hopes of reaching a third successive World Cup final before England inflicted another setback on the coach who had turned Les Bleus into one of world football's dominant forces.
"The disappointment is there on a sporting level," Deschamps said. "We had the opportunity to create emotions for tens of millions of French people. It is the World Cup, there is nothing more beautiful."
The French Football Federation paid a glowing tribute to Deschamps, who leaves after 185 matches and 120 victories in charge.
"Didier Deschamps embodied high standards, rigour, a sense of the collective and love for the blue shirt," the FFF said in a statement.
"Under his leadership, for 14 years, the France team regained credibility, respect and affection while remaining at the highest level in the world."
Deschamps led France to the 2018 World Cup title and 2021 Nations League crown as well as the Euro 2016 and 2022 World Cup finals.
The FFF said his quarter-century of service to the national team, stretching from his years as captain to his time as coach, had left an "indelible mark."
"Few will have given as much to the blue shirt as a player and then as coach," it said.
Deschamps captained France to their first World Cup triumph in 1998 and won the European Championship two years later before becoming only the third man to win the World Cup as both player and coach when Les Bleus triumphed in Russia in 2018.
His final match provided none of the controlled, disciplined football that came to define much of his tenure, but the chaotic defeat did little to diminish a legacy that transformed France into one of the most consistent teams of the modern era.
"Thank you, Didier," the FFF said.
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FIFA World Cup 2026
The 2026 World Cup is taking place from June 11th to July 19th in the United States, Canada and Mexico. The tournament features 48 national teams and is played at 16 modern stadiums.
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