LaBeouf was arrested for disorderly conduct, public intoxication and obstruction of justice while filming the movie in 2017.
“I felt very protective of him and I felt very like, that’s a really terrifying and difficult journey for somebody to experience. And I felt really aware of that,” Johnson told The Ellen Show.
“We were there to make this movie and [co-star] Zack [Gotsaggen] is really a phenomenal human being and… you feel very awake to the truth of life and humanity and love and people and real connections when you’re with him.”
Johnson continued: “I think that that [arrest] was just a kind of a very important moment for Shia. I don’t condemn people for their mistakes. I want them to get through it, so that’s what I tried to do.”
During his arrest in Savannah, Georgia, LaBeouf was caught on video using racially charged language towards a black police officer.
"What went on in Georgia was mortifying," he previously told Esquire. "White privilege and desperation and disaster... It came from a place of self-centred delusion... It was me trying to absolve myself of guilt for getting arrested."
LaBeouf credited Gottsagen for changing his behaviour.
"Everybody was pussyfooting around it," said LaBeouf, while Gotsaggen told him: "You’re already famous. This is my chance. And you’re ruining it.”
LaBeouf said: "To hear him say that he was disappointed in me probably changed the course of my life.”
The Peanut Butter Falcon is out in UK cinemas now, and LaBeouf’s new semi-autobiographical film Honey Boy, in which he re-enacts the arrest, will be released on 6 December.