A MAN suffering from dementia was assaulted after a Facebook post warning about his behaviour around children at Semaphore went viral.

Police received reports that the man was approaching children and parents, pulling faces at them and trying to engage them in conversation.

A member of the public uploaded several pictures of the man to Facebook and late Friday afternoon the man was pushed off his bike.

The man’s adult children took him to the Port Adelaide Police Station and police believe the assault is linked to the Facebook post.

No offences have been committed by the man, according to police.

Earlier this month in Melbourne, controversy erupted after a mother shared a photo of a man she mistakenly assumed was taking pictures of her kids.

The first line of her post read, “OK people, take a look at this creep.”

The man was actually taking a “selfie” next to a Darth Vader cut-out to send to his kids.

The post was then shared hundreds of times on Facebook where the man’s partner eventually saw it.

He was abused by strangers on the street on his way to the police station to clear up the misunderstanding, and said the episode had left him shattered.

“I felt sick. I am so embarrassed and devastated,” he said.

The woman who posted his photo later met him privately to apologise.

Police warn people to not take matters into their own hands and avoid posting potentially defamatory material online.