Morrison cut short his trip to Hawaii as criticism of him increased, the BBC reported.
One person was found dead on Saturday, and wildfires were raging in three states.
Since September, Australia's bushfire emergency has killed at least nine people, destroyed more than 700 homes and scorched millions of hectares.
"I get it that people would have been upset to know that I was holidaying with my family while their families were under great stress," he said.
Speaking after a briefing with fire officials, he said he knew Austral were anxious about the fires, but insisted that the emergency response was "the best in the world".
He conceded that climate change was contributing to changing weather patterns, but denied that it had directly caused Australia's wildfires.
"It's not a credible suggestion to make that link," he argued.
Many Austral have accused Scott Morrison's government of inaction on global warming, with criticism growing as a heatwave broke records across the country and worsened the fires.
Morrison also paid tribute to Geoffrey Keaton, 32, and Andrew O'Dwyer, 36, the two firefighters killed in New South Wales on Thursday.
"When our volunteers go out there, they do it for so many reasons, but I can't help thinking they do it for love of family. Family is community, and they were out there defending their communities on that fateful night," he said. The two men died when their truck was hit by a falling tree near a fire front, causing it to roll off the road.
Rising temperatures and strong winds worsened fires in three states.
( With inputs from IANS )