The ombudsman, Marie Anderson, released details of her investigation on Monday.
Mrs Anderson said: “Given restrictions on gatherings at the time, I am satisfied that there was reasonable justification for the PSNI to have attended the scene.
“However, after examination of all evidence, I was of the view the arresting police officer had not responded in line with an order to treat the gathering with sensitivity.”
In a statement, PSNI Chief Constable Jon Boutcher said the force accepts recommendations made by the ombudsman.
More to follow.