Earlier this year, Mickelson, a San Diego native, indicated an interest in being part of the group that bought the team in August.
On Tuesday, Mickelson told UT San Diego that he had withdrawn his interest in doing so.
"I think to be involved with the Padres, you have to be fully committed to the long term," Mickelson told the newspaper. "I've been born and raised here, but at this moment, I'm not able to make that kind of long-term commitment to the city and to the team."
As recently as October, Mickelson said that it looked promising that he would still be involved with the ownership group.
In August, when the sale of the team was complete and the ownership group was announced, some were surprised that Mickelson was not part of the group, especially after he expressing interest previously.
Peter Seidler, who is part of the ownership group, was asked that day about Mickelson's involvement.
"We think Phil is a great fit with our group," Seidler said. "Phil and I are going to get together in two weeks when he's back in town, and I think we both expect we will formalize. We have one spot in our ownership group for Phil and only Phil."
In August, the Padres announced the completion of the sale of the club to the Seidler/O'Malley group and executive chairman Ron Fowler for $800 million from former majority owner John Moores.
On Aug. 16, Major League owners approved the transfer of the franchise from Moores -- who owned the team for 18 years -- to the group headed by Fowler.