Lane Garrison on Surveillance Video Slap: Deceiving!

Lane Garrison, who was arrested for domestic violence on Saturday, says the surveillance video of him apparently slapping his ex proves ... that he did not.

Lawyers.

The actor and his ex-girlfriend got into a verbal argument that turned physical and the surveillance video (below) showed what appears to be Lane Garrison slapping Ashley Mattingly's face hard, which he told cops never happened.

He still says that, and here's why:

Lane Garrison Slaps Ashley Mattingly

Lane told Beverly Hills detectives that what really happened was Ashley grabbing his phone and him reaching to grab it back from her. No slap at all.

Lane says he ended up grabbing Ashley Mattingly's cell phone, not his own ... and that's when she threw his phone against the wall and smashed the thing.

He says when he walked out, he childishly threw her phone in retaliation. If you look at the video closely, Lane Garrison's scenario is at least plausible.

He also claims he has text messages from Ashley that are incriminating and that she didn't want him disclosing - hence the freakout over the phone.

Garrison, who is still on parole for his manslaughter DUI conviction, is still being held in connection with this case and a possible parole violation.