Real have flattered to deceive in domestic football this season, and sit third, 15 points behind their eternal rivals.
Zidane, though, believes that the challenge of maintaining performance across 38 games is more difficult than lifting the Champions League.
"It's more difficult. I've always said that: it's more difficult," he said when asked about the difference between La Liga and European competition.
Though Barcelona have won the title, they will not receive a guard of honour from Los Blancos at Camp Nou, despite the tradition of applauding the league winners onto the field.
And Zidane claims that the gesture is rooted in a snub that dates back to the Club World Cup, which Real won in December.
"After the Club World Cup, it wasn't important for them to give us a guard of honour," he added.
"It's said that they weren't in the competition, but that's not true. You get into it through the Champions League. They didn't give us one.
"What's most important is respecting what they've done: They've won the double and I respect that, and I congratulate them on that. We're not going to do something they didn't do."
Zidane also scoffed at suggestions that he could field a weaker team with one eye on the Champions League final.
"No, not at all. I'm not going to think about that. If that were the case, there'd be no point playing tomorrow or in our remaining league games. If a player isn't at 100 per cent, though, he won't play; but as for the rest, they'll play as always."