"You can’t condone that kind of behavior in any shape or form," he said.
Scott reshoot all of Spacey's scenes with Christopher Plummer, only weeks before the flick is due to hit the cinema.
But he admitted that he was "totally" happy with Kevin Spacey's performance in his new movie 'All The Money In The World', but conceded that not cutting him would "affect the film".
He added: "You can’t tolerate any kind of behavior like that. And it will affect the film. We cannot let one person’s action affect the good work of all these other people. It’s that simple."

Scott revealed that he has not spoken to Spacey since he decided to cut him out of the movie.
"No. And he didn’t call me. If he had called me and said, 'Hey, look, this is the way it is and I’m really sorry,' then I’d have handled it slightly differently," he said. "I would have said, “Yes, thank you for calling, but I have to move on.”
He said that Christopher Plummer, who starred in the classic 'The Sound of Music', had been his first choice to play the part.
But he had went with Kevin Spacey originally because the film studio wanted a big name in the role.
On how he went about recasting Plummer in the role, Scott told Entertainment Weekly: "Chris [Plummer] was always on the list. So you find that out, but quietly, because you don’t want it going around. I flew into New York and met with [Plummer] and he said yes.
"So then we had to figure out if everyone else would be available to fit in these new days of shooting. Miraculously, they were.
"Before you can make the decision you have to make these quick phone calls around — not to the actors directly, but to the agents — saying there’s a possibility I may need some pickups [a.k.a. additional shooting days].
"You don’t say why because of the gossip, but of course it was really for something much more significant."
Asked if he had been surprised by all these revelations coming out of Hollywood, Scott responded: "I think it was about time. Harvey [Weinstein] definitely was way overdue. There will still be a few more people out there gritting their teeth who are way overdue."