MIKE TYSON PLEADS SELF DEFENSE IN PAPARAZZI FIGHT! HE'S BEING SUED FOR $25 MILLION!

Mike Tyson claims he needed to get aggressive with a paparazzo at LAX last year because he felt the photog had put him in "immediate danger" ... this according to legal docs.
The docs were submitted in response to a $25 million lawsuit filed earlier this year -- in which Tyson was accused of assaulting and battering Antonio Echevarria in an airport terminal last November.

In the new papers, Tyson claims he doesn't owe the guy a single penny because he was provoked -- and insists that he merely acted in a manner that was "necessary for his self-defense" and the "protection of others."

As we previously reported, Echevarria shot footage of the incident -- which was heavily edited before we got a hold of it -- showing an angry Tyson charging towards the photog and saying, "I will kill you."

Tyson was arrested moments after the incident -- but the L.A. City Attorney ultimately rejected the case citing "insufficient evidence."