The victory, courtesy of Mario Mandzukic's 12th league goal of the season and captain Philipp Lahm's effort, extended their unbeaten run in the Bundesliga to 45 games, while it was only their second win at the Grundig Stadion in seven attempts.
"I saw immediately why Bayern have won here in the last six years, only once," Guardiola told reporters.
"Nurnberg were very aggressive and [played a] very intense game. They attacked very quickly and had two or three clear chances.
"At 2-0 it was a bit easier for us. It was difficult to play well here - especially for our short passing game."
Bayern lead the way in the Bundesliga with a 13-point gap to second-placed Bayer Leverkusen. Nurnberg, meanwhile, remain in the relegation play-off spot one point behind Freiburg.