The PSNI was forced to intervene after a man ran at East Belfast MP Naomi Long as she addressed hundreds of people at the anti-cruelty rally.
The man was seen being restrained by two officers as he ran towards the stage at the gates of Belfast City Hall and appeared to shout abuse at the Alliance politician, who is a vociferous campaigner on animal rights.
As police removed the man from the area in front of City Hall, one rights protester with a dog could be seen trying to speak to him.
He was taken away from the crowd, in the direction of Donegall Place, and he didn't get close to the MP.
The Belfast Telegraph contacted Ms Long but she didn't want to comment on the incident.