Tarek Mitri said at United Nations headquarters in New York that security, particularly in the east, had deteriorated, describing as "huge" the number of arms and ammunition across Libya.
The supreme court had earlier ruled Miitig's election as unconstitutional, ending a month-long standoff in the interim parliament that saw two rival cabinets jostle for power.
Mitri welcomed the ruling as "important" and the fact that it had been accepted as "a sign of hope."
Asked how security in Libya compared to six months or a year ago, he said: "The situation has deteriorated, especially in the east. There is no doubt about that."
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Near daily attacks in the eastern city of Benghazi, cradle of the 2011 revolt against dictator Moamer Kadhafi, have killed dozens of members of the security forces.
"One thing we can all see is that there are arms and ammunitions in huge quantities all over Libya. And not just arms in the hands of the army and police but in the hands of everybody including criminals," said Mitri.
Mitri told the UN Security Council that there had been no sustainable progress on disarmament and reintegration of armed groups, and that insecurity impeded the proper functioning of the justice system.
Courts in the cities of Derna, Benghazi and Sirte had stopped working for prolonged periods to protest attacks against prosecutors, judges and other state officials, he said.
Mitri said UN-facilitated dialogue was "more crucial than ever" ahead of a June 25 election to elect a 200-member council to replace the interim parliament, or General National Congress.
He said any "resort to the use of force will have disastrous consequences for the country.