Has the UN ever intervened in a conflict involving Libya?

Yes the un has intervened in a con flict involving libya
YES. One of the more famous interventions was UNASOG, which was a UN Peacekeeping Operation established to verify the withdrawal of the Libyan administration and forces from the Aouzou Strip in accordance with the decision of the International Court of Justice. UNASOG was disbanded after Chad and Libya both declared the Libyan withdrawal to have completed.

The toppling of Muammar Qadhafi in 2011 was a NATO operation and did not come under the purview of the United Nations.