"I think it’s kind of silly," the 72-year-old said on the podcast A Life Of Greatness. "I mean, this movie was made in the 1970s about the 1950s."
Newton-John played high schooler Sandy Olsson who falls for local bad boy Danny Zuko (John Travolta).
"Grease" aired over Christmas 2020 on the BBC and prompted people to express their opinions on Twitter, according to the UK Express.
One person said, "The drive-in/botched make-out session between Danny and Sandy hasn’t aged well. Film kinda glides right into song ("Sandy") before viewers register the date rapey vibe of the scene they just saw #Grease."
Another said, "Ahhh man. Just watching #Grease one of my favorite films and it’s so of its time. Misogynistic, sexist and a bit rapey."
Someone else pointed out there was very little diversity onscreen. "There were no Black actors or pupils at the high school," they wrote.
Newton-John pointed out, "It was a stage play, it’s a musical, it’s fun. It’s a fun movie musical not to be taken so seriously."
The actress added that people on the Internet "need to relax a little bit and just enjoy things for what they are... I think it’s a fun movie that entertains people."
Newton-John, who has been battling cancer since 2017, recently told People magazine, "I don't think I imagined living this long! I feel very blessed."
She noted how she's "feeling great," and also discussed how her husband, John Easterling, has helped her throughout her battle with breast cancer with the use of cannabis.
"I'm very lucky to be married to a wonderful man who is a plant medicine man, and he has great knowledge," she described.
Newton-John is looking forward to her daughter, Chloe's, upcoming wedding. The singer gushed, "She is my reason to be."
Fox News' Andy Sahadeo contributed to this report.