Ms O’Brien said she was “in awe” of Nikita Hand and her civil court victory proved to other victims that “you still have a voice”.
The protest was organised by ROSA, a socialist feminist movement, as part of International Day for the Elimination of Violence against Women.
The protesters marched from Dublin city hall, along the River Liffey and to the office of the Irish director of public prosecutions (DPP) to express concern at the failure to take a criminal case against McGregor.
A higher legal threshold applies to a criminal case than a civil case.
In a criminal case, the burden of proof is beyond reasonable doubt, while in a civil case, it is on the balance of probabilities.
