Northern Ireland Secretary Peter Hain has said the feuding between the UVF and the LVF is "gangsterism masquerading as loyalism".
The murder of Michael Green has been linked to the feud
Since the start of July, four murders have been linked to the feud between the two loyalist paramilitary groups.
Mr Hain said the police need support to help end the violence.
The PSNI had already carried out 90 searches and arrested 20 people - charging 10 of them - in relation to the feud, he said.
"What is important at this time is to bring an end to this violence and intimidation through effective policing and the PSNI deserve the support of the whole community especially in loyalist areas," Mr Hain said.
Northern Ireland Office officials "are in close contact with community leaders in loyalism to try to bring this ongoing violence to an end", he added.
He said NIO ministers also remained in close contact with the police about the situation.
Assistant Chief Constable Duncan McCausland said police were getting "considerable support" from the public in their efforts to halt the violence.
"We are getting significant results and significant assistance from the community," Mr McCausland said.
However, he urged the community to "redouble their efforts" in helping his officers.
The latest killing to be linked to the feud was that of 42-year-old Michael Green, who was shot at close range by two gunmen as he arrived for work at a shop in south Belfast's Sandy Row area on Monday.
The Loyalist Volunteer Force has blamed the Ulster Volunteer Force for the killing, but an LVF source denied Mr Green was one of its members.