RUMER WILLIS has offered to treat her mother Demi Moore to a mommy makeover, but a source says the aging actress isn’t interested!

“Rumer thinks her mom is gorgeous,” said a pal. “But she also thinks that Demi needs to start looking more mature.

“Demi’s worn her hair long, straight and parted down the middle for the past dozen years, and Rumer would like to see her in a shorter, more chic hairstyle.

“Demi is also known for wearing sexy thigh-high skirts, but she’s turning 52 in November, and Rumer feels she needs to lower her hemline.”

Starlet Rumer, 25, also worries that her cougar-licious mom will have her heart broken by her latest beau, 27-year-old musician Sean Friday.

“Rumer is afraid that when Sean is ready to start a family, he’ll find a younger woman – just like (Demi’s ex) Ashton Kutcher did with Mila Kunis,” said the source.

“She knows how crushed Demi was when Ashton moved on, and she doesn’t want her mother to go through that again.”

Rumer – the eldest of Demi’s three daughters with ex-hubby Bruce Willis – has even offered to scour an online dating site like to find her mom a mate, said the source.

“Demi is convinced that if Rumer does that, she’d end up with an older guy who’d rather sit home watching ‘Dancing with the Stars’ than go out and dance the night away,” said the source.

As for Rumer splurging on an all-expenses-paid makeover for her, the source said: “Demi thinks it’s sweet that her daughter is concerned, but she feels that as long as she’s still turning heads with her long hair and short skirts, she’s going to keep on doing it!”