The teen was held on the ground for an extended period of time until journalists appealed to the Anning supporters to allow the person to get back on his feet.
Far-right activist Neil Erikson, who was involved in the gang-tackle, shouted at the organisers to remove reporters.
“Get the journalist out of here… If you don’t like, get out,” he said.
Police are investigating the incident and Senator Anning’s retaliation.
The teenager has been released without charge pending further investigions.
He earlier delivered an impromptu speech to about 100 supporters at Moorabbin in Melbourne’s south-east, in which he doubled down on his comments blaming Muslim immigration for Friday’s Christchurch shooting.
When Senator Anning also said many of his supporters in his home state of Brisbane were under 35, one person from the crowd noted that the alleged Christchurch shooter was aged 28.
“It’s the younger generation taking up the fight”, said the supporter.
Anning responded: “well he’s obviously a little on the crazy side, but yeah.”