Second teen arrested after elderly man pushed off pier

Days after the arrest a 14-year-old boy, police are expected to charge a 17-year-old male from Hastings on summons after he was interviewed and released on January 17.

The incident unfolded about 11.30pm on January 14 at the popular beach spot about 70km south of Melbourne.

Footage uploaded to social media shows a group of males walking along the pier at night before they spot the man walking towards them.

One of them is heard urging another "go, go, go" before he's filmed pushing the man into the water.

The group runs off laughing as one yells, "yeah the boys!".

Onlookers pulled the man from the water and he was not seriously injured, according to Victoria Police.

State Member for Mornington Chris Crewther said it was an "absolutely despicable incident", in a Facebook post.

He said the 79-year-old victim couldn't swim and was "very much shaken up".

Mr Crewther thanked the "brave people" who jumped in to help the man out of the water, and encouraged the victim to come forward to police.

In a statement police said officers were called to reports a man was allegedly assaulted and pushed into the water off a pier near Schnapper Point Dve in Mornington.

A 14-year-old Crib Point boy was charged on summons with reckless endangerment and unlawful assault.

Both teenagers will face a children's court at a later date and the investigation remains ongoing, police said.