Lopez, a 42-year-old divorced mother of 4-year-old twins, has been part of the "Idol" judges' panel alongside Randy Jackson and Steven Tyler for the past two years, but she won't return to the show next season, the insider said.
"There is just too much going on for her right now," the source told UsMagazine.com.
"She regrets she can't stay on the show," the insider said. "It's been an incredible experience and she is forever grateful that she did it."
Lopez recently admitted to the magazine she is "a little tired right now."
"I'm not going to lie," said Lopez, who is planning a concert tour this summer and recording a new album. "I've been rehearsing, doing 'Idol,' promoting this movie ['What to Expect When You're Expecting'] ... the kids, it's a lot of stuff!"
However, she also said she feels "really in the zone."
"I feel really good about everything. I feel like everything's going so well. I feel blessed. I do," she said.