A total of 11 people were arrested during Union flag protests in Belfast and Derry last night.
PSNI officers called on a number of homes yesterday and cautioned that participation in demonstrations could lead to prosecutions.
In the seven weeks since the Union flag controversy began, PSNI officers have monitored hundreds of protests.
Nine men and two women were arrested during protests last night.
At weekend protests, PSNI officers handed out leaflets, suggesting that wearing a mask could be considered an offence and they also called on a number of homes and issued cautions.
Community groups, church leaders and paramilitary organisations have all called for an end to rioting in east Belfast.
Business leaders have also warned about the damaging effect of the protests on the economy.
Protests began when Belfast city councillors voted on 3 December to restrict the flying of the Union flag above City Hall.