The Bafta-nominated star quit acting in 2014, following the release of The Other Woman, Sex Tape and Annie.
The Hollywood actor hasn't appeared in a film since 2014.
The Charlie's Angels star said she found years of working and being in the public eye "intense".
Being a mother to her baby girl is the "best, best, best part of my life," the actor said.
Cameron Diaz And Benji Madden Welcome Their First Child Together - And Reveal Their Daughter’s Unusual Name
It is the couple's first child together.
Kristen Stewart, Naomi Scott and Ella Balinska lead the new reboot, directed by Elizabeth Banks.
Cameron Diaz and Drew Barrymore came out to support their co-star nearly 20 years after the original movie.
"The truth is I’m embarrassed and it makes me cringe now. I’m deeply sorry."
“I got a lot of sh** for it,” the Aerosmith rocker confessed to James Corden.
A former costar previously said Diaz had called it quits, but then said she was joking.