The hosts poured players forward in the first half but could not take the lead as Arjen Robben, Franck Ribery and Mario Mandzukic all missed opportunities at the Allianz Arena.
Hannover began the second half with intent and almost opened the scoring themselves as Leonardo Bittencourt had a close-range effort blocked, and although Mandzukic and Ribery found the net within 20 minutes after half-time, Guardiola was still not impressed.
He told SID: "Hanover have played very well. For us, a game after an international break is always difficult.
"We were not tired, but after an eight or nine-day break, the rhythm was missing something.
"In the second half we played better after the goal. Now we are ready for the Champions League on Tuesday."
Bayern goalkeeper Manuel Neuer bemoaned his team's performance in the first half and felt things would have been far more comfortable if they had made the most of their chances.
He added on Bayern TV: "I think you maybe have seen it. We had to get the tiredness out of our legs and if we had played a little bit better in the first half we would definitely have got more good chances which we usually convert into goals."
One of Bayern's better performers during the match, Robben, admitted, though, that being tired after an international break could not be used as an excuse, even if players had returned from all over the world.
He said: "Of course, we have the quality and we get our chances, but I think we have to play better.
"It can't be an excuse that it is the first match after the trip with our national teams, even though we all came back from anywhere – it can be difficult, they say. But we just have to concentrate (and be) ready."
