Meghan Markle said public figures have a basic right to privacy and should not have to grant the media full access to their personal lives.
Meghan, the Duchess of Sussex, made the comments in an unbroadcast segment of her interview with Oprah Winfrey on Sunday.
The original broadcast was watched by more than 17 million viewers in the US and 11 million in the UK.
Ms Markle opened up about the intrusion into her private life while she was dating Prince Harry and as a married royal.
She was asked by Winfrey if losing a degree of privacy was to be expected because of her high-profile status.
"I think everyone has a basic right to privacy. Basic. We're not talking about anything that anybody else wouldn't expect," Meghan said.
She likened the intrusion to a co-worker asking you to share pictures of your children.
"If you're at work and you have a photograph of your child on your desk, and your co-worker says, 'Oh, my gosh, your kid's so cute. That's fantastic! Can I see your phone so I can see all the pictures of your child?' You go: 'No. This is the picture I'm comfortable sharing with you'," Meghan said.
"And then if they double down and say, 'No, but you already showed me that one. So you have to show me everything. You know what, I'm just gonna hire someone to sit in front of your house, or hide in the bushes and take pictures into your backyard, because you've lost your right to privacy ... because you shared one image with me,'" she said.
The public is not entitled to demand unrestricted access to the lives of high-profile people, she said.
"There's no one who's on Instagram or social media that would say, 'Because I shared this one picture, that entitles you to have my entire camera roll. Go ahead and look through it.' No one would want that. So, it's about boundaries. And it's about respect."
Ms Markle won a legal victory in February against the Mail on Sunday after a court ruled the newspaper breached her privacy by publishing a private letter.
The letter, to her estranged father Thomas Markle, was written a few months after she married Harry, and asked him to stop talking to tabloids and making false claims about her in interviews.
