Matthew McConaughey Mentors Son Levi on Set of Teen's New Movie

Matthew McConaughey is making sure his 16-year-old son, Levi, is doing alright, alright, alright on the set of his big break ... TMZ has learned.

In video footage obtained by TMZ ... the Oscar winner is seen reassuring his and Camila Alves' son, who is on set at Mission Beach in San Diego filming his breakout role in the movie, "Way of the Warrior Kid."

Levi clearly appears nervous before one particular take, turning to his famous dad -- who is not involved in the film -- for advice.

Eyewitnesses tell TMZ ... Levi was set to do a pull-up scene, and visibly had the jitters before shooting it ... which is why he turned to his dad for some veteran advice.

Matthew gives Levi a loving tap on the shoulder, offering up words of encouragement and sending the teen on his way to film his scene.

We're assuming everything went according to plan, as MM returned to the video village after the father-son chat.

Word of Levi's casting in "Way of the Warrior Kid" -- an adaptation of Jocko Willink's book of the same name -- dropped in September, when it was announced that LM had been cast in a supporting role in the Chris Pratt-led film.

The film also stars Linda Cardellini, Jude Hill, and Ava Torres.