The impact of the result left Germany coach Christian Wuck dumbfounded as he concluded that his side failed to deliver on the evening.
"It's hard to find words," he said. "None of my players found the level they can play, but in the end Iran were very aggressive, strong and fast. We had too much respect for them."
Quizzed weather the heat, complacency or a brilliant Iran side played more of a role in their defeat, Wuck replied, "All those aspects contributed to the fact that Germany could not perform to a good level. Let's say that Iran played a great match and we didn't play at our level.
"I told my players that during their careers they will face many setbacks and this is probably one of their biggest setbacks but we have to come back strongly against Guinea."
The former Wolfsburg player acknowledged their Tuesday's opponents' strengths but refused to single out one player from his squad for putting up a mediocre performance.
"We knew in advance that Iran are physically very strong so we also wanted to field strong players. All the players, not only the goalkeeper (Luca Plogmann) were not at their best," he lamented.
Should Iran be branded as the contenders to win the U17 World Cup? Wuck responded, "I don't know. They played a very good game against us and against Guinea also. They are mentally a very good team."
Germany and Guinea, who drew 2-2 against Costa Rica on Tuesday, will play their last group stage fixture at the Jawaharlal Nehru International Stadium at Kochi which will kick-off at 17:00 IST on Friday, October 13.