Blatter again defended the decision to award the 2018 and 2022 World Cups to Russia and Qatar but said announcing the choices at the same time may have been a mistake.
"This is a justified question after a year of ups and downs," Blatter told reporters after a FIFA Executive Committee meeting in Tokyo on the sidelines of the Club World Cup.
"It was not the best and most intelligent decision of FIFA to announce the two World Cup simultaneously," said the 75-year-old on the eve of Barcelona's final with Santos in Yokohama.
"It was wrong and it caused a lot of disturbances earlier this year," he added of the controversy and subsequent blaze of corruption revelations triggered by the choices.
"The past is past and we have to look forward. The boat is still not in still waters but we are bringing it back to port.
"Regrets, yes. But you can't live in regret. You can have regrets but you can't go back and change the past,
"You must have have a positive approach and I have the energy to go forward and bring back the credibility of FIFA and take care of public opinion."
Blatter, re-elected for a fourth term in June unopposed after then Asian football chief Mohamed Bin Hammam was booted out of FIFA in a cash-for-votes scandal, has his work cut out.
The Swiss provoked negative headlines last month by saying any incidents of racist abuse on the pitch should be settled with a handshake after the game.
Blatter said his comments had been misunderstood and rejected widespread calls for him to resign.
QATAR DEFENCE
Having launched new anti-corruption measures in October, Blatter again defended the choice of surprise winners Qatar for the 2022 World Cup against outside criticism.
"The 2022 World Cup will be in Qatar and I don't know who can change this decision," said Blatter, responding to remarks made by new Australia football boss Frank Lowy.
"I personally will intervene if FIFA executive members continue with such declarations [accusations]. I understand about the incident in Australia but the case is closed now."
He added: "The World Cup shall be accessible to all cultures and it was time... to bring it to the Arab world."
Lowy was quoted last month as saying the tiny Gulf state, whose bid was dogged by corruption allegations, could still be stripped of the 2022 finals.
Qatar's bid leaders strongly denied any wrong-doing but emotions still run high as the beleaguered FIFA president did his best fire-fighting job.
"Our reforms are on the right track," said Blatter, coming up for air briefly to announce Morocco would host the 2013 and 2014 Club World Cup tournaments.
"FIFA will respond to public opinion."
Blatter's pledge to reopen the case into the collapse of former marketing partner ISL has also been stalled after being tied up in a Swiss appeals court.
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