The Catalans won the competition on the final day of the season after crushing Real Valladolid 4-0 on Sunday.
Arch-rivals Real Madrid were held to a 1-1 draw by Malaga but they would not have been able to catch Barcelona anyway.
Guardiola, who steered Barca to six titles in 2009, reveled in a seventh triumph but could not hide his disappointment at their failure to reach the Champions League final.
Barcelona suffered a 3-2 aggregate loss to Italian champions Inter Milan in the competition's semi final.
"This is a day for great celebration and after winning three titles last season we have won four more," Guardiola said.
"It was a really tough season and small details stopped us getting through to the Champions League final in Madrid.
"We owe the fans. We had to be in the final on Saturday but we aren't and we will try to win it next season."
Santiago Bernabeu, the home of Real Madrid, will host the Champions League final between Inter and German champions Bayern Munich.