Australian environmental authorities were investigating the allegations that he breached regulations governing how close people can get to wildlife in the Antarctic.
But the exuberant Australian entertainer best known for wrestling crocodiles on his popular television show denied any wrongdoing, saying he had only climbed onto an iceberg after his dry suit ripped while his company was filming the whales.
"My dry suit had ripped, so it was leaking water, and here's this iceberg, a little iceberg ... so I grabbed hold of the iceberg and I'm sitting on the iceberg while these whales are just all over us," he added.
Irwin called media reports of his latest run in with authorities "just a big storm in a tea cup."
Parliamentary environment secretary Sharman Stone confirmed Irwin's company was granted approval to film whales. But Stone said the permit would not have allowed Irwin to jump in and pat the animals.
The probe followed anwhen Irwin was shown on television feeding a large crocodile at his Australia Zoo in Queensland state while holding his baby son.
Irwin, the TV host of the "Crocodile Hunter" wildlife program, stunned onlookers by carrying his son, Bob, then only a month old, into a crocodile pen during a show in January. He tucked the infant under one arm while tossing the 13-foot reptile a piece of meat with the other.
Irwin, who gained fame in the 1990s with his show on the Animal Planet network, dismissed suggestions he had endangered his son, saying he kept the baby safely in his arm farthest from the crocodile.
He apparently was reported to authorities by people on a passing ship who thought they saw him riding on a whale's back.
"What happened mate was, when we were down in Antarctica, these two beautiful humpback whales ... came up to our boat," Irwin told Australian television's Nine network on Monday.
Stone said authorities also were concerned about clips of Irwin's upcoming documentary "Ice Breaker," which is due to air on the Animal Planet network on Friday.
The clips show Irwin and penguins skimming down a slope, though it is unclear how close he is to the penguins. Another clip shows him lying on rocks close to a leopard seal.