Gunther Steiner ensured Haas' two drivers "cleared the air" after a clash in the Spanish grand prix.
"We had contact and that is something that must not happen. But it happened," Magnussen told the Danish broadcaster TV3.
Team boss Steiner dealt with the matter immediately.
"I asked them both to come to me straight away. It was one of those episodes where we need to understand what happened and not make quick conclusions," he said.
Steiner would not say what the outcome of the meeting was, beyond revealing: "We cleared the air between all three of us. We'll move on from here."