The New York Post said Flea answered fan and media questions about why the musicians' instruments weren't plugged into amps during their performance of "Give It Away" with halftime headliner Bruno Mars.
"It was made clear to us the vocals would be live but the bass, drums, and guitar would be pre-recorded," Flea wrote on the Red Hot Chili Peppers website Tuesday.
"For the actual performance, [we] were playing along with the pre-recorded track so there was no need to plug in our guitars, so we did not. Could we have plugged them in and avoided bumming people out who have expressed disappointment that the instrumental track was pre-recorded?" he said. "We thought it better to not pretend."
The Post said Mars sang live, but his band also used a pre-recorded music track.