Mickelson, who earlier said he was sorry for the comments in an interview with Fox News, reiterated the mea culpa at the pre-tournament press conference for the Farmers Insurance Open in San Diego, USA Today reported.
"I've made some dumb, dumb mistakes, and obviously talking about this stuff was one of them," he said.
The California resident Sunday told reporters the passage of Proposition 30 by state voters in November -- which raises taxes on millionaires -- would mean "drastic changes" for him, intimating he was considering leaving the state.
He also cited a federal tax deal that would raise taxes on the wealthy.
The comments ignited a political debate, which Mickelson -- who made an estimated $47.8 million in 2012 -- again said he regretted, the newspaper reported.
"I made a big mistake talking about this stuff publicly, and I shouldn't have done that," he said. "I think that it was insensitive to talk about it publicly to those people who are not able to find a job, that are struggling paycheck to paycheck."