The bassist has revealed that leaving the band has run through his mind several times, especially when former guitarist John Frusciante quit the group back in 2009.
"Oh, I've considered pulling the plug a million times. That's nothing new for me," Flea told Guitar World magazine.
"Things get to be a bummer and I start going, 'Mmm, this is kind of a drag.' And I just couldn't imagine doing it without John."
Flea added: "When he did up and leave, though, some time went by and I just started feeling this deep love for the band and wanted to continue it. Plus, I missed Anthony. So we got Josh."
The Red Hot Chili Peppers will release their tenth studio album I'm With You on August 29 in the UK and August 30 in the US.
The band recently announced plans to play a one-off show at London's Koko on September 2.
Watch the music video for Red Hot Chili Peppers' new single 'The Adventures Of Rain Dance Maggie' below: