Cruz spoke to CNN's Dana Bash Wednesday, and the elephant in the room was addressed ... his official Twitter account had "liked" a porn video on Monday night ... which showed up to his 3 million-plus followers.

The Texas senator made it clear -- it wasn't him. A male staffer "screwed up" and "hit the wrong button." Cruz also said he wasn't gonna out the "fella" who did it, 'cause it was accidental and wouldn't happen again.

Dana asked if the staffer would be punished, and Cruz deflected, saying it'd been dealt with internally. In other words ... the guy's still got a job.