Sanders found himself at the centre of controversy earlier this week after it emerged that he had a 'fling' with Twilight star Kristen Stewart, with whom he worked on Snow White and the Huntsman.
However, Michael Sanders has now insisted that his son is a "very honourable" man.
"From what I gather nothing really happened and it is all a lot of fuss about nothing," he told People. "I should imagine it was something very brief.
"She is a very pretty girl and when you work that closely with someone for so long, sometimes things happen."
Michael, who described his son as "hardworking" and a "dedicated father and filmmaker", also suggested that Rupert and his wife Liberty Ross will stay together.
"Of course their relationship will survive this," he said. "This is nothing - they will definitely survive all of this. It is all a lot of fuss about nothing."
Both Sanders and Stewart issued public apologies after the fling emerged, while Ross apparently tweeted about the situation before deleting her account.
Meanwhile, reports have claimed that Stewart's partner and fellow Twilight star Robert Pattinson is "heartbroken" and "humiliated" after learning about the tryst and is now considering whether or not to forgive her.
He is also thought to have left the home they shared in Los Angeles.
Photo gallery - Robert Pattinson and Kristen Stewart's relationship in pictures:
> Lady GaGa: 'I hope Kristen Stewart, Robert Pattinson are okay'
> Kristen Stewart 'was Rupert Sanders's wife's pick for Snow White role'
> Robert Pattinson asked "why do people cheat" before Stewart fling
> Kristen Stewart shares intimate dinner with Rupert Sanders - pictures
> Rupert Sanders wife: 'I felt like I was raising children alone'