Three goals in a devastating nine-minute spell at the start of the second half saw Barcelona to a 4-1 win over Athletic Bilbao in the King's Cup final on Wednesday and the first of three possible titles.
Yaya Toure levelled for Barca in the first half before Lionel Messi, Bojan Krkic and Xavi struck after the break to give the club their 25th King's Cup.
The Catalans could wrap up the Primera Liga title this weekend and they face Manchester United in the Champions League final on May 27.
"The title is a reward for the players and all the people who have worked so hard to get us here," Guardiola told reporters.
"Now we need to win the league as soon as possible so we can can prepare well for the Champions League final in Rome."
Barca had an unfamiliar look in defence with reserve keeper Jose Manuel Pinto in goal and Yaya Toure at centre back again, and they were quickly exposed at a set piece.
Pinto had tipped a Javi Martinez shot round the post and Fran Yeste made it count. His whipped-in corner after nine minutes found Gaizka Toquero rising above two defenders to head in at the back post.
Athletic looked fresher, snapping at Barca all over the pitch, until Toure stepped up to level in spectacular fashion as he advanced out of defence.
The Ivory Coast midfielder went past three Bilbao players in the 31st minute, and from outside the area drilled a low shot inside the near post.
Gradually Barca asserted themselves and as they swarmed round the Bilbao area in the 55th minute it was Messi who struck, firing through a crowd of legs after Gorka Iraizoz could only parry Samuel Eto'o's shot.
Three minutes later, Bojan raced through on a break to score off the far post and with Bilbao reeling Xavi curled a superb freekick over the wall and in off the near post in the 64th.
Just before Xavi's goal the match was held up briefly after Barcelona defender Daniel Alves was hit on the head by a tin can thrown from the stands.
Alves was able to continue and television pictures showed police leading a fan away.
Athletic, who have won the cup 23 times, were a broken team after that, but earn a place in next season's Europa League with Barca's place in the Champions League assured for next year.
Bilbao's Spain striker Fernando Llorente told Radio Marca: "In the first half we had some chances, but in the second half they were much better.
"We did what we could, but we were up against one of the teams who will go down in history."