Loyalists tried to kill a police officer when they set fire to his patrol car in Belfast on Monday.
A gang of 15 men tossed a petrol bomb into the unmarked vehicle after surrounding and smashing it outside the offices of Alliance Party MP Naomi Long.
Speaking about the incident on Tuesday morning, MP Long said her heart was "breaking" for Northern Ireland.
Loyalists have fought with police on the streets of Belfast again
"It's time for the British Government to stand up and not turn a blind eye to this violence," she said.
The petrol bomb came during another night of sporadic violence in parts of east and south Belfast involving loyalists who took to the streets again in protest against a decision by Belfast City Council to restrict the flying of the union flag at Belfast City Hall.
PSNI Assistant Chief Constable George Hamilton said one officer was lucky to escape with his life outside Long's office on the Newtownards Road. They were treating the attack as attempted murder.
Officers were also attacked with petrol bombs in south Belfast close to the M1 motorway.
He said: "This was a planned attempt to kill a police officer which also put the lives of the public in danger and it is fortunate there were no injuries."
Peter Robinson, the Northern Ireland First Minister and leader of the Democratic Unionist Party had talks in Belfast on Monday with Mike Nesbitt, leader of the Ulster Unionist Party to try to agree some sort of agreed political strategy in a bid to ease tensions and end the violence on the streets.
They have been heavily criticised by nationalist representatives over their leadership since the trouble first flared a week ago.
The trouble followed a council decision to limit the flying of the Union flag to designated days only.
Ms Long's Alliance Party has been blamed by the loyalists for supporting the nationalist SDLP and Sinn Fein in pushing through the vote to lower the flag.
A police car that was hit by a petrol bomb as a new outbreak of sporadic trouble occurred in parts of east and south Belfast
There were also protests in Limavady, Co Londonderry, Ballyclare, Co Antrim, Ballycastle, Co Antrim and Cookstown, Co Tyrone where the car of a DUP member of the Northern Ireland Assembly, Ian McCrea, was surrounded by angry loyalist who were angry at his presence.
Several roads in Belfast were blocked and at one stage police were also attacked with petrol bombs and fireworks at Broadway, not far from the M1 motorway.
Last week Ms Long was told by police to stay away from her home and her office on the Newtownards Road because of fears for her safety.
Constituency offices used by the party were also attacked in Carrickfergus, Co Antrim and Bangor, Co Down.
Mr Robinson and Mr Nesbitt have already called for loyalist restraint, and according to a statement they agreed to work on a "joint basis with a view to urgently bringing forward political proposals to address widespread concerns across the community".
More talks are planned for Tuesday.
Naomi Long, whose offices were targeted with petrol bombs
Ms Long said there could be no justification for the vicious attacks.
She added: "If Northern Ireland is to move forward then we need a strict adherence to the rule of law and respect for the democratic process. We need this urgently before lives are lost."
She said the attacks were "madness" and called for the British Government to step in to stop the violence.
Speaking to BBC Breakfast on Tuesday, she said: "Last night's attack on two officers guarding my office was a wanton and gratuitous act of attempted murder.
"It's time for the British Government to stand up and not turn a blind eye to this violence.
"There needs to be strong political leadership at this time and not simply left to the police to deal with."
She added: "My heart is breaking for Northern Ireland this morning.
"We cannot give in to the acts of violence.
"We owe it to the people of Northern Ireland to keep the peace process intact."
Theresa Villiers, secretary of state for Northern Ireland is set to make a statement in the House of Commons about the "despicable" violence.
"There is no justification for rioting, and violence and attacks on police officers," she told Sky News. "That is why it is absolutely essential that these incidents of violence stop."
Meanwhile in Armagh city, Sinn Fein accused masked loyalists of attacking a bar, the Cuchulainn, after staging an impromptu march with no police presence.
They claimed windows were smashed and fireworks thrown. A statement said: "The protests, intimidation and violence needs to end and unionist politicians need to be to the fore using whatever influence they have in ensuring this happens."
PSNI Chief Constable Matt Baggott said the some of the violence was intense and there was clearly some paramilitary involvement.
It was fortunate someone was not seriously injured, he claimed, adding that the situation in some areas was very tense.
He said: "There has to be a collective voice to bring this to an end."
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