The European champions could have scored four or fives times in an electrifying start to their quarter-final first leg in London on Wednesday.
That attacking display earned praise from all quarters despite Barca only coming away with a 2-2 draw on the night.
"Eleven shots in 15 minutes as happened against Arsenal only occurs once in a lifetime," Guardiola told reporters as he sought to play down expectations ahead of Saturday's visit of Athletic Bilbao in La Liga.
"We can't go out tomorrow expecting a repetition. We have to try and maintain the same work rate as the first half against Arsenal."
"It's my job to make sure that they don't think about anything else other than Athletic Bilbao," he said.
"The game at the Bernabeu is the least important of all the games in La Liga. The world doesn't end there. I would prefer to win all the remaining games than the one there.
"(After the "Clasico") There are still 21 points to play for, every one of those games as difficult as the one at the Bernabeu."
Barca and Real are level on 74 points from 29 games, with Manuel Pellegrini's side top on goal difference.
After next Saturday's "Clasico" the head-to-head record will decide first place if they remain level on points, and could decide the league title come the end of the season.
