Trent Dilfer Apologizes For Shoving H.S. Player ... In Sideline Meltdown

NFL QB-turned-H.S. football coach Trent Dilfer is expressing his regret over a wild blowup on one of his players over the weekend ... saying he was flat-out wrong to shove and yell at the kid.

49-year-old Dilfer -- who won Super Bowl XXXV with the Baltimore Ravens -- went viral for unleashing on Lipscomb Academy star Beau Dawson (yeah, NFL kicker Phil Dawson's son) ... getting in his face and pushing him in an attempt to get him to sit on the bench during a game on Friday.

Now, Dilfer is apologizing for the whole incident ... releasing a statement via the team and praising the young player in the process.

"First and foremost, I take full responsibility as the head coach and leader of our team…