There have already been 181 arrests and 128 charges in connection with the unrest which has followed changes to Belfast City Hall's flag policy.
Detective Superintendent Sean Wright said the images are linked to serious trouble in east and south Belfast, and Newtownabbey, in recent weeks.
He said the PSNI remains committed to the investigation.
"We are today releasing 19 images of individuals whom we'd like to talk to in connection with ongoing investigations into serious public disorder and I'm hopeful that the wider community will help us identify these individuals," he explained.
"I also encourage the persons within these pictures to contact my team directly - in doing so they will minimise the impact on themselves, their family and their community.
"The ongoing protests and associated disorder has caused havoc and serious disruption for local people and local communities. It is in everybody's interest - as well as in the interest of justice - that those responsible are dealt with appropriately. I would urge anyone who may have information to bring it forward."
Over 100 police officers have been injured since the trouble started in December.
Fifty of those arrested so far have been juveniles.
Detective Superintendent Sean Wright continued: "Young people are limiting their life choices in terms of future employment and travel prospects.
"People with certain convictions may not be able to apply for Visas or travel to certain countries in the future and we want them to understand that the decisions they take now may have a great impact on the choices they may wish to have later in life.
"Parents also need to take responsibility - know where their children are and what they are doing. It is important for parents to discuss these issues with their children to ensure they fully appreciate the impact of such actions and the fact that such activity could constitute a crime for which they could be arrested and face charges."