Barca top the standings with 87 points, just one ahead of Real Madrid with four games to go, and must bounce back quickly after being dumped out of the Champions League at the semi-final stage by Jose Mourinho's Inter Milan side on Wednesday.
"The players are down and sad but we have to pick ourselves up. On Saturday we have La Liga and we have to go out and win," Guardiola said after their defence of the European Cup ended.
Barca's aura of invincibility is slipping after winning six trophies last year and they only have the league left to focus on now.
Manuel Pellegrini's side have won all but one league match at the Bernabeu this season and are supremely confident Barca will stumble on the run in.
"We have a strong chance of winning the league," Brazil midfielder Kaka told a news conference.
"The dressing room believes we can do it. One point isn't much of a difference and we are confident we can overhaul Barca if we win all our remaining games."
On Sunday, fifth-placed Sevilla receive Atletico Madrid in a dress rehearsal for next month's King's Cup final between the two sides.
