Germany came to Belfast in need of a win after a bitter 4-2 home defeat by the Netherlands in Hamburg last Friday left them in danger of dropping out of the automatic qualification spots.
Yet Monday's victory saw them knock Northern Ireland off the top of Group C, ending a spotless run of four wins in four for Michael O'Neill's side.
"We were under pressure after the defeat to the Netherlands," Loew told broadcaster RTL.
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His team's nerves showed in the first half, before goals from Marcel Halstenberg and Serge Gnabry sealed the three points after the break.
"We had to overcome a few problems in the game -- the Northern Irish were brave and attacked us early on," said Loew, and admitted that his team should have killed the game off earlier.
"We were better in the second half. We are in a learning phase," he said.
Loew's young team struggled against a fearless Northern Ireland side in the first half.
Conor Washington forced an early save from goalkeeper Manuel Neuer, and nearly bundled the ball in at a goalmouth scramble shortly before half-time.
Left-back Halstenberg broke the deadlock with an inch-perfect half-volley just after the break, smashing a bouncing ball into the top corner to pick up his first-ever international goal.
A string of chances followed for Germany, with Marco Reus and Timo Werner both forcing saves from Bailey Peacock-Farrell.
Having ridden out the storm, Northern Ireland quickly began to expose Germany's defensive frailties again and almost equalised through Stuart Dallas just after the hour mark.
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Yet Bayern Munich winger Gnabry finally sealed the win two minutes into injury time, squeezing the ball past Peacock-Farrell from the tightest of angles.
Germany now leapfrog Northern Ireland to go top of Group C on goal difference, with both sides having picked up 12 points from their opening five games.
The Netherlands, who have played only four games so far, sit in third with nine points after their 4-0 victory over Estonia.
Despite their four wins so far, O'Neill's side still have a mountain to climb to qualify, as they face two clashes with the Dutch and a trip to Germany in their remaining five games.
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