The chairman of the Anti Divorce Campaign, Mr Des Hanafin, was attacked by an unidentified man close to Leinster House.
Mr Hanafin was badly shaken but not seriously hurt after a man rushed up and struck him as he stood outside the National Museum last Friday afternoon.
Mr Hanafin said he believed the attacker struck him because of his anti divorce activities.
The assailant ran off, chased by some onlookers, but was not caught.