Police are searching for a "brazen" thief who allegedly snatched $1,000 in cash from an 80-year-old woman at an ATM machine on Christmas Eve.

Key points: Police said the thief appeared to target a "vulnerable" member of the community

Police said the thief appeared to target a "vulnerable" member of the community The man snatched the cash from the woman's hand after she used the ATM

The man snatched the cash from the woman's hand after she used the ATM Police are appealing for help from the public to identify the man captured in CCTV footage

The Western Australian woman, who was in Melbourne on a Christmas holiday, had just withdrawn cash from the machine on Toorak Road in Melbourne's inner-east when she was robbed, police said.

CCTV footage of the incident shows a man standing behind the woman at the ATM and holding a phone to his ear, before suddenly lunging towards her.

Constable Declan Barbagallo said the man appeared to be deliberately targeting "a vulnerable member of the community".

"A male has walked up behind her, appearing to be on the phone," he said.

"He's waited for her to finish her transaction. As the money has come out, he's approached her, grabbed the money from her hand and has then fled the scene."

The man is described as Caucasian, and aged in his 20s to 30s, with black hair, a beard and a moustache.

Community help sought to solve 'shocking' crime

Constable Barbagallo said the woman was "shaken up" by the incident, and unfortunately no bystanders were present to assist.

He said staff from the ANZ bank branch comforted the woman after the robbery, and she was being supported by her husband and daughter.

"We're seeking assistance from the community to identify the male. Obviously it's a pretty shocking crime," Constable Barbagallo said.

He said it was not clear from the footage whether the man had been loitering in the area in the lead-up to the offence.

"But it's pretty clear that as soon as someone's approached the ATM, he's stood up behind them," he said.

Anyone with information or who may recognise the man is urged to contact Crime Stoppers.