Independent senator Lidia Thorpe has been pulled to the ground after attempting to interrupt anti-trans-rights campaigner Kellie-Jay Keen-Minshull at a rally outside parliament.

Ms Keen-Minshull was speaking to a small group of protesters huddled under a marquee in the rain when Senator Thorpe, draped in the Aboriginal flag, crossed the street and attempted to enter under the marquee.

Senator Thorpe could be heard shouting "you are not welcome", before being pushed back by a man in a suit and pulled to the ground by a police officer.

Video footage shows officers initially attempting to help Senator Thorpe back on her feet, until she crawls away from the crowd and then stands up to join pro-LGBTQ counter-protesters a short distance away.

In a statement, the Australian Federal Police (AFP) said the incident would be reviewed.

"The interactions between the AFP and protesters will be reviewed, and an incident has been referred to the AFP’s Professional Standards Command," it said.

"Given a matter is now under investigation, no further comments will be made."

Speaking to reporters shortly after the incident, Senator Thorpe said Australia should be "ashamed" that it had let Ms Keen-Minshull into the country.

"I went to tell her, or that 'thing', that they are not welcome here and I got pulverised by the police for simply telling that person they are not allowed to be here," Senator Thorpe said.

"I have been assaulted by police today."

Senator Thorpe has been contacted for comment.

While rallies outside parliament are common, the planned anti-trans-rights rally for today had drawn extra interest after a rally in Melbourne organised by the same group was attended by neo-Nazis.

After state Liberal MP Moira Deeming participated in the rally, the Victorian Liberal leader vowed to have her expelled.

Federal politicians were drawn in when Liberal MP Sarah Henderson intervened in an attempt to save her party colleague.

But today's rally in Canberra had so far failed to draw more than a handful of supporters, as well as a crowd of pro-LGBT people who had attended to protest against that rally and outnumbered them.

One Nation senators Pauline Hanson and Malcolm Roberts, as well as senator Ralph Babet, had arrived to support Ms Keen-Minshull, but no politicians from either major party were present.

Inside parliament, the focus has been entirely elsewhere, with the government coming to its final position on the wording of the referendum on whether to enshrine an Indigenous Voice to Parliament in the constitution.