Speaking at a Paris meeting, National Transitional Council (NTC) head Mustafa Abdel Jalil promised a new constitution and elections within 18 months.
French President Nicolas Sarkozy, who chaired the meeting, stressed the need for "reconciliation and forgiveness".
He said air strikes would go on as long as ex-leader Col Gaddafi was a threat.
Mr Sarkozy said all 63 nations at the meeting were committed to returning frozen assets to the Libyan people.
Col Gaddafi has still not been captured by the interim authorities.
In an audio message broadcast on a loyalist TV channel on Thursday, he vowed he would never surrender.
He was speaking on the 42nd anniversary of his emergence as Libya's Leader, which until last year was an occasion for annual celebrations in the country.
This year there were flag-waving celebrations in Tripoli's main square to mark the date - only the flags were the black, green and red colours of the NTC rather than the all-green of the Gaddafi regime, and the square is now known as Martyrs' Square, rather than the Green Square.
Mr Sarkozy held the conference jointly with UK Prime Minister David Cameron - the two leaders who were instrumental in passing the UN resolution that allowed Nato forces to intervene in Libya.
And both men stressed that Nato would continue its involvement as long as it was needed to protect civilians.
"We are determined to continued with Nato strikes for as long as Mr Gaddafi and his supporters represent a threat to Libya," said Mr Sarkozy.And Mr Sarkozy said everyone had agreed to unfreeze assets blocked when Col Gaddafi was still in power.
"After going around the table, it's about $15bn of Libyan assets in our countries that are immediately unfrozen," he said.
He added that the NTC must engage in reconciliation in order to avoid the mistakes made in other countries.
Mr Cameron urged the council to make sure perpetrators of the "unspeakable crimes" that were coming to light in Tripoli were brought to justice.