It was a third league championship in three years for the Catalan club but it was a far from vintage performance as they contented themselves with a point at the Ciutat de Valencia stadium where they also won the 2005 league title.
The draw left them on 92 points with two matches left, six ahead of arch-rivals Real Madrid who they bettered in head-to-head matches 6-1.
"Winning the league was been extremely tough and we are very pleased," Guardiola told reporters.
"We have been tremendous for three quarters of the season but in the last quarter we have struggled to score goals.
"If we have experienced a dip in form towards the end of the season, it is because of the inhuman schedule over the last two years. We have barely stopped."
World Player of the Year Messi has scored 31 times in the league campaign.
"I'm delighted because it has been a very difficult title to win," he said.
"We've had to work very hard to be champions and more so against a great rival like Real Madrid. Now we have to enjoy it."
NINE TROPHIES
Guardiola's three-year reign as coach, his first top-flight management job, has brought Barca nine trophies including three league titles, one European Cup and one King's Cup.
Barca have reached the last four of the Champions League every season and face Manchester United in this year's final in London on May 28.
Eight of the current Barca squad also won the World Cup with Spain in South Africa last year.
Barca have struggled with injuries, particularly in defence, with Carles Puyol, Adriano Correia and Maxwell all sidelined, along with Eric Abidal who needed surgery on a liver tumour.
"We need to reinforce in some areas, there are things we can improve on," Guardiola said, looking forward to next season.
Abidal made his first start back in the side against Levante, and Guardiola described the defender's return as one of the highlights of the campaign.
"The worst part of the season was what happened to Abidal," Guardiola added. "But, his recovery was also the best."
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