Second-half goals from Arkadiusz Milik and Sebastian Mila led Poland to their first ever win over the world champions.
Nawalka said the aim was always for victory as his side made it six points from two games in Group D.
"I am delighted with the result. We set out to win the game, but on the other hand you can't give too much space to Germany," he said.
"When you play against the reigning world champions you also need a bit of luck.
"This win puts us in a good position in the table after getting six points from the first two qualifiers. We won the game and made history as this was our first ever victory against Germany."
Poland goalkeeper Wojciech Szczesny praised Nawalka for his tactics, and said they were happy to welcome the visitors attack them.
"Of course we were not favourites to win this game, but our tactics worked well," he said.
"We let Germany come into our half and attack us, but in defence we managed to control them.
"Of course, we were in trouble at times during the first half, but that is normal that if you play against the world champions.
"It was great to beat the world champions in my home city, I enjoyed it, but we are already focusing on Tuesday's game against Scotland."
