Zoe Saldana's children still haven't watched 'Avatar'.

The 44-year-old actress starred in the 2009 sci-fi movie - but Zoe insists that her kids are still "too young" to watch the record-breaking film.

Zoe - who has eight-year-old twins Cy and Bowie, and Zen, six, with her husband Marco - explained: "My kids tend to be very vocal about what is appropriate for them and what is inappropriate, and they have just such gentle hearts."

Zoe has reprised the role of Neytiri in 'Avatar: The Way of Water', and the actress loves being involved with the movie franchise.

She told PEOPLE: "It felt like the gift that keeps on giving.

"We were a part of something so groundbreaking, so trailblazing. It resonated with so many people around the world that it only felt fair to come back again."

Earlier this year, Zoe claimed that her children keep her "out of trouble".

The Hollywood star also believes that her children are one of the keys to her youthful appearance.

She shared: "I think having children keeps me out of trouble a lot. I go to bed early. I eat better. I sleep longer sometimes. I'm back to sleeping."

Zoe has changed her lifestyle since becoming a mom, and she's now much more self-disciplined than she's ever been.

The actress - who married Marco in 2013 - said: "I was having a lot of problems with my sleep. Whereas right before I had them, I was very much of the policy of work hard, play hard.

"And I loved my life like that. But I feel like having children happened at the right time for me because in your mid-thirties to late thirties, early forties, that's when you go to bed thinking that you're one thing, and you wake up feeling like something else."