over an hour to break down the Wolves defence on Saturday to stay second in the Bundesliga.
Manchester City warmed-up for the visit of the European champions with a 3-2 defeat at Aston Villa to leave Manuel Pellegrini's side fifth in the Premier League, but Guardiola said Bayern must tighten up.
"We won, but we must improve a lot of things," admitted the Spaniard ahead of the trip to England and next Saturday's Bundesliga clash at third-placed Bayer Leverkusen.
"We had a few problems in the second half which we need to solve. I am certain that we will put in a good performance in Manchester and at Leverkusen."
Bayern and City are battling for top spot in Group D after winning their opening matches with Munich seeing off CSKA Moscow 3-0 at home and City winning 3-0 at Viktoria Pilsen.
But against a dogged Wolfsburg defence Bayern's finishing and passing let them down in a below-par performance.
Guardiola took off Arjen Robben, Bastian Schweinsteiger and Mario Mandzukic in the second-half with one eye on the trip to England, but Bayern were far from impressive.
They only created 11 shots on goal all game and too many sloppy passes allowed Wolfsburg to contain the European champions for the majority of the match.
Germany midfielder Thomas Mueller scored the winner with his first Bundesliga goal of the season when he met Franck Ribery's pass from the left wing at the far post on 63 minutes.
"We presented ourselves well in terms of how we battled away," said Mueller.
"Wolfsburg gave us nothing and it was far from a walk in the park for us. They played almost man for man against us, which gave us a few problems and we can be pleased that we won.
"We deserved the win as, apart from a couple of chances, I didn't see much from Wolfsburg.
"The set up for our goal was excellent and I am pleased that I have now scored in the Bundesliga."
Borussia Dortmund prepared for their Champions League clash at home to Marseille on Tuesday with a 5-0 rout of 10-man Freiburg to stay top of the Bundesliga.
Dortmund ran riot at Signal Iduna Park with Germany winger Marco Reus and Poland striker Robert Lewandowski scoring twice before Polish midfielder Jakub Blaszczykowski added the fifth 10 minutes from time.
"I was already happy with the first-half. We had wanted to find our rhythm from the first second, which we did," said Klopp, whose side need to win on Tuesday after losing 2-1 to Napoli a fortnight ago.
"We put in a good performance and it was a lot of fun to watch."