The Bavarian giants lost their 100% home record after being held to a 3-3 draw with Hoffenheim in the Bundesliga this afternoon.
Bayern travel to Old Trafford on Tuesday for their first-leg quarter-final clash, and the Spaniard is keen for a much-improved display.
"Compliments to Hoffenheim," Guardiola told his club's official website. "They showed a good ability to press.
"In the first half we found good solutions. In the second half, though, we were not good. We need to control the ball. If this is not the case, then we have a problem.
"We need to analyse this game and then quickly focus on Tuesday. We need to improve."
Tuesday's clash is scheduled to kick off at 7.45pm.