Violent protests against a former IRA bomber who tried to kill a prime minister have damaged their own community, Northern Ireland's First Minister Peter Robinson said.
Four police officers suffered minor injuries as protesters threw fireworks and stones at a centre in east Belfast where Brighton bomber Patrick Magee was a guest speaker on Thursday night.
Mr Robinson said: "The actions of those who attacked the Skainos Centre and the police are to be condemned. Those rioting on the streets did not challenge republicans; instead they took the focus away from a debate which heard how the republican terror campaign ended in failure.
"Protest is a legitimate part of our freedoms which must be protected but only when carried out within the law."
Magee plotted to kill former Conservative Prime Minister Margaret Thatcher and her Cabinet during a party conference.
He hid a bomb in a hotel bathroom wall with a timing device set for 24 days ahead. I t exploded as the Tory party slept - killing five people and injuring more than 30 others.
Magee was given multiple life sentences but released early under the Good Friday peace agreement which largely ended the conflict.
Sir Anthony Berry MP was among those who died in Brighton.
His daughter Jo Berry now works with her father's killer in an organisation promoting peace and conflict resolution throughout the world.
They attended the east Belfast conference together, taking part in a festival called: Listening to Your Enemies.