Senior US State Department official Jeffrey Feltman said after talks in Tripoli on Wednesday that Washington respected the right of Libyans to decide their own future after the ouster of Moamer Gaddafi.
"The United States respects Libya's sovereignty," said Feltman, the highest ranking US official to visit the Libyan capital since its capture from Gaddafi's forces on August 23.
"A guideline of our partnership with the Libyan people will be always be respect for Libya's independence and sovereignty," he told a news conference.
"This is a victory by the Libyan people and Libya's destiny must be decided by Libyans alone."
Feltman, the assistant secretary of state for Near Eastern affairs, was in Tripoli for a lightning one-day visit during which he held talks with the head of Libya's National Transitional Council, Mustafa Abdel Jalil.
Feltman paid tribute to the work of NTC in overseeing the transition from Gaddafi's 42 years of iron-fisted rule.
"In this interim period, the (NTC) has assumed enormous responsibilities in charting a path through this challenging transition and living up to the peaceful and democratic aspirations of the Libyan people," he said.
He said US Secretary of State Hillary Clinton had been reassured by a statement issued by the NTC on Tuesday in which it renewed its commitment to respecting human rights and promised to investigation allegations of abuses following a damning report by Amnesty International.
"This includes respect of for the universal rights of all men, women and children in Libya," Feltman said.
"I told chairman Jalil that Secretary Clinton particularly welcomed his recent restatements of the (NTC's) commitments to human rights, reconciliation and to inclusive transition progress, recognising the important roles of women and youth."
In Tuesday's statement, the NTC executive committee said it strongly condemned any human rights abuses perpetrated by either side in the seven-month uprising against Gaddafi's regime after Amnesty detailed allegations of torture and reprisal killings by rebel fighters.
"The NTC strongly condemns any abuses perpetrated by either side," the NTC statement said.
"The NTC is putting its efforts to bring any armed groups under official authorities and will fully investigate any incidents brought to its attention."
In its report, the London-based human rights watchdog said dozens of people suspected of being former security agents, Gaddafi loyalists or mercenaries had been killed after capture in eastern Libya since February.
A US advance team headed by embassy number two Joan Polaschik arrived in Tripoli on Saturday to make preliminary contacts, and assess the material condition and security of the embassy, the State Department said on Monday.
The team reported that "the water situation, the electricity situation, essential services, do seem to be coming back to normal," spokeswoman Victoria Nuland said.
Reopening the US diplomatic mission with ambassador Gene Cretz at the helm should be a question of weeks not months, Nuland added.
The NTC chief arrived in Tripoli from his wartime base in Libya's second-largest city Benghazi on Saturday and was given a hero's welcome.
A crowd of hundreds mobbed Abdel Jalil at the airport and he had to be protected by a thick human chain.
The interim leader has said he has only returned to the capital on a temporary basis and that he will only set up base permanently Tripoli once the liberation of Libya from pro-Gaddafi forces is complete.