Union flag protests which devastated traders in Belfast before Christmas could be repeated this year, First Minister Peter Robinson warned.
Loyalists reacted after Belfast City Council decided to restrict the flying of the emblem from City Hall to designated days. Dozens of police officers were injured during riots linked to some rallies and sectarian fighting erupted between loyalists and nationalists.
Mr Robinson said: "I have heard of some proposals to hold protests leading up to the Christmas period.
"I hope people will reflect on the damage that would cause to Northern Ireland and to traders in Belfast, potentially leading to a loss of jobs."
Rioting loyalists broke into City Hall on the night of a controversial vote to change the dates of the flying of the union flag from the building from every day to only on designated occasions like royal birthdays.
Tensions have been high in loyalist communities since the violence last December, with nightly protests extending well into January. A troubled loyal order marching season injured many more police officers.
Much of the violence centred on a contested parade through North Belfast, with loyalists attacking police with swords and other weapons.
The Parades Commission, which adjudicates on the route, barred the parade from the Ardoyne, after a history of associated violence.
The Orange Order is still protesting in an effort to march through the flashpoint area.
A recent separate loyalist demonstration in the busy Royal Avenue shopping area descended into a riot, with scaffolding used to attack police.