WATCH: Quentin Tarantino snaps in press conference

Quentin Tarantino snapped at a reporter who questioned Margot Robbie's lack of screen time in 'Once Upon a Time in Hollywood'.

The 56-year-old director brushed off the question from a female writer at a press conference at the Cannes Film Festival on Wednesday and refused to elaborate on her enquiry.

Asked why Margot, who plays Manson family victim Sharon Tate in the movie, didn't have more to say or do, he said: "I reject your hypothesis."

this is painful to watch pic.twitter.com/9PwvMgTMYo

— courtney (@infamousmargot) May 22, 2019

But the 28-year-old actress stepped in instead and insisted she had a lot of time to "explore the character" and didn't need scripted lines to "honour" the tragic starlet.

As her director looked upset, Margot said: "I think the moments I was on screen gave a moment to honor Sharon.

"I think the tragedy was the loss of innocence. To show the wonderful sides of her could be done without speaking. 

"I did feel like I got a lot of time to explore the character without dialogue, which is an interesting thing. Rarely do I get an opportunity to spend so much time on my own as a character."

Margot took on the role because she felt she was able to "honour the memory" of Sharon Tate.

She added: "Quentin said to me she's the heartbeat of the story. I saw her as a ray of light."

Elsewhere during the 30-minute question and answer session, Tarantino explained why he felt people are fascinated by Charles Manson and his followers.

He said: "I think we're fascinated by it because at the end of the day, it seems unfathomable.

"I've done a lot of research on it. How he was he was able to get these girls and young boys to cement to him seems unfathomable. The more you learn about it, the more information you get, it doesn't make it any clear. It makes it more obscure."