Rioting sparked by the re-routing of an Orange Order march was "not loyalism but gangsterism", Northern Ireland Secretary Peter Hain has said.
Mr Hain said the violence was tearing communities apart and has got to stop.
He is set to meet Chief Constable Sir Hugh Orde, who described the violence as "the worst faced by police in the United Kingdom in recent years".
He said shots were fired at officers by "loyalist paramilitary groups firing from the cover of the riot".
He said the outlawed UDA and UVF had "taken advantage" of "what could have been a lawful parade which went completely outside the determination given by the Parades Commission".
"There was no ceasefire ongoing yesterday - I'm absolutely clear about that," he added.
Trouble broke out after a disputed Protestant Orange Order parade in the Whiterock area of west Belfast.
At the weekend, Sir Hugh had said the Orange Order bore substantial responsibility for the rioting and attacks on his officers.
The Orange Order described his remarks as "inflammatory", but Sir Hugh rejected this.
"We are not in a position to be on one side or the other - every single time, my officers are absolutely in the middle," he said.
He called for politicians, Orangemen and community leaders to "be responsible, rather than to walk away and leave it to police officers to try and fix".
Mr Hain said it was wrong to say that the violence was symptomatic of a feeling by loyalists that they were losing out.
"The difficulty with Northern Ireland for a long time, and it remains, is that whenever one side is seen to gain the other side sees it as a loss.
"However, what we had at the end of July was an historic IRA statement, taking away the whole basis of the conflict between Catholics and Protestants, between nationalists and loyalists.
"And therefore it's very difficult to see this particular episode over the weekend or indeed the wider concern - some bitterness and anger within unionist and loyalist circles - as part of the traditional pattern of Catholic against Protestant, loyalist and unionist politics.
"And I think there's now a need for leadership on all sides, particularly from the Orange Order, from loyalist groups, from the unionist parties, to try to find a way forward."