The "Ocean's Eleven" star, 49, went under the knife several years ago to remove excess skin around his eyes and he owned up to the procedure in a 2007 interview on "The Oprah Winfrey Show," admitting, "It's important to look awake."
But Clooney is convinced people in their twenties shouldn't be using surgery to boost their self-esteem.
He tells Britain's Hello magazine, "It's fine for other people and if people want to do something that makes them feel better, good luck to them.
"The times I worry are when I see some of the younger people out there messing with their faces because I think that's a mistake. I worry about people who are so unhappy with the way they look that they start trying to look younger at 25."