Fighting escalated in the northwestern city of Misurata on Monday, after NATO airstrikes damaged buildings in Libyan leader Moamer Gaddafi's compound in the capital Tripoli, dpa reported.
Gaddafi's forces increased their shelling and use of tank fire in residential areas of the city, regional broadcaster Al Jazeera reported.
The attacks come despite an earlier announcement by the government that Gaddafi's forces would withdraw from the city after eight weeks of continuous fighting with rebels.
NATO said it carried out airstrikes in Tripoli in the early hours of Monday targeting a communications headquarter used by Gaddafi's forces to coordinate attacks against civilians.
Government officials took foreign journalists in Tripoli to see buildings in Gaddafi's Bab Al Aziziya compound, which were damaged by NATO. A press official from Gaddafi's government said the attack was an attempt on the leader's life.
Saif al-Islam, one of Gaddafi's sons, said that NATO is losing its battle against Libya, because "Moamer Gaddafi has millions supporting him."
"To all Libyans, this is a cowardly attack because it took place in the darkness of the night, and is only meant to terrorise children, and it is impossible to make us feel afraid, give up or raise the white flag," Saif al-Islam said shortly after the attack.
The airstrikes came as fighting in Misurata left dozens of people dead on Sunday after the government announced a retreat from the city, saying that local tribes would be left to settle the issue, either by force or through negotiations.
A witness who requested anonymity told the German Press Agency dpa that residents in neighbouring communities had given the Libyan army an ultimatum to defeat the rebels quickly. When the deadline was not met, the tribes vowed to deal with the rebels themselves.
The rebels say at least 1,000 have been killed in Misurata, Libya's third most populous city, about 200 kilometres east of Tripoli.
NATO has been in control of military operations in Libya for over three weeks to protect civilians from Gaddafi's troops and enforce a United Nations no-fly zone over the North African country.
Unlike pro-Gaddafi forces, "we continue to go to great lengths to reduce the possibility of any civilian casualties," NATO said in a press release on Monday.
"We will keep up the pressure until all attacks against civilians have stopped," Gaddafi's forces "have withdrawn to bases and full and unimpeded humanitarian access has been ensured," NATO Spokesperson Oana Lungescu said.