Libyan air force attacked Haftar's positions today
Libyan rebel groups plan to continue marching on Tripoli after government forces used airstrikes to repel the advance.
The sides have been in an uneasy truce since shortly after Gaddafi's downfall but the country now risks falling into civil war. The oil rally on Friday was partly due to concern about Libya's 1.3 million barrels per day of production.
A joint statement from the G7 on Saturday expressed the "deepest concern" after a meeting in France.
The UN Security Council called on him to "halt all military movements."
The movements from Haftar came as a surprise with the UN in the country to broker peace with UN-backed Prime Minister Fayez al-Sarraj.
On Friday Haftar's spokesman said the offensive would only end once Tripoli fell.