VENICE, Italy — Playing First Lady Jacqueline Kennedy in Chilean director Pablo Larrain’s “Jackie” felt “somewhat dangerous,” Natalie Portman said Wednesday, “because everyone knows what she looked like, sounded like, and has kind of an idea of her.”

The Oscar-winning actress told reporters in Venice that the role “was terrifying, because I never really thought of myself as a great imitator… I was just trying to get to something that people could get past and believe I was Jackie, and then you always have yourself in there too, inevitably.”

Portman spoke at a packed news conference after the press screening of “Jackie,” which world-premiered to positive reviews at the 73rd Venice Film Festival. Asked if the unconventional bio-drama presented her with her most challenging role to date, Portman replied: “I think it’s definitely up there.”

The movie depicts the four-day period right after President John F. Kennedy was assassinated, and is Larrain’s first film in English.

“You of course know I’m not American. I’m not necessarily attached to its history as I am to my country,” said the director, whose film “Neruda” impressed critics in Cannes in May.

Larrain said part of the inspiration came when he read the Warren Commission report describing the president’s death and noticed “that Jackie was sitting next to him.”

“I thought: Why don’t we take her point of view?”

The film depicts the public and private personas of the former first lady, which Portman said were quite different.

“Looking at the existing film and audiotape of Jackie, we noticed that her voice and her presence were very different” depending on the context, she said.

“There were a lot of small details of how she presented herself as the wife of a politician, which were so different from when she was talking to her old friend Schlesinger [Arthur Schlesinger, Jr.] in the tapes, during which you can hear the ice clinking against their glasses in the background. It’s a much different tone,” Portman noted.

“There are so many feelings at once that she is going through… The film comes at her from so many different aspects. She’s a young widow; she’s a symbol for all these people; she’s a mother; she’s a wife — a betrayed wife; she’s a person who is trying to figure out her way in the world,” Portman said.

Larrain said that in order to capture the vividness of Portman’s performance, the camera and crew had to stay extremely close.

“I remember, on the first day of shooting, we set the camera in one spot, and then I asked Natalie to come closer, and she came closer. And then I said, ‘Can you please just come closer?’ And then I said, ‘Again, closer.’

“That was [throughout] the whole movie. It was probably hard for her having so many people so close to her all the time. But I wanted to be very, very close and intimate,” he said. “That’s how you get to really feel the process she went through.”