The Sweden forward, who spent just one year in Spain, told Italy’s Gazzetta dello Sport: "Guardiola wants to appear perfect in public. Tiger Woods is the same. But no one is perfect."
He also took aim at what he believed was Guardiola's inexperience.
"He's a great manager but with little experience, and still too young to manage a team with 22 stars with different personalities."
Guardiola guided Barcelona to six trophies in 2009 but Ibrahimovic commented: "It's not difficult to win at Barcelona. With such a team, who couldn't win?"
He had more favourable words for Jose Mourinho, his coach at Inter in 2008-09, and who he will cross swords with again on Tuesday when AC Milan face Real Madrid in the Champions League.
"'Mou' motivated me, he's a winner...Mourinho comes, he wins, then says goodbye and thank you."
This is not the first time Ibrahimovic has taken Guardiola to task.
Last month the 28-year-old striker dismissed his former Barca manager as "a small time" coach.
"In my book, a great coach solves his problems. A small-time coach runs from them," Ibrahimovic told a press conference in Stockholm.
"There was only one person (on the Barcelona team) who wanted to get rid of me," he insisted, explaining why he left the team and signed for AC Milan on an initial one-year loan with a pre-arranged 24-million-euro permanent deal arranged for the end of the season.
While Guardiola has declined to respond in public Barcelona president Sandro Rosell labeled Ibrahimovic's purchase from Inter as the worst financial mistake in the club's history.
"It's Barca's worst transaction, but I think that we sold quite well, having bought badly," he said on Sunday.
Ibrahimovic joined Barca from Inter in the summer of 2009 for a club-record fee of €46 million ($64 million), with Cameroonian striker Eto'o -- valued at €20 million -- moving in the opposite direction as part of the deal.
The Swede helped Barca win the league title last season but failed to fit into Guardiola's playing strategy.
He joined AC Milan this summer on an initial loan deal with a €24 million purchase clause, to be paid in three installments of eight million euros over the next three years.
Barca's general director, Antoni Rossich, said Ibrahimovic's departure represented a loss of €33.4 million for the club.
Ibrahimovic's AC Milan take on Real Madrid in the Champions League on Tuesday.
Golf star Tiger Woods' perfect image was shattered last year following revelations of a series of extra-marital affairs.