A huge banner placed on the medieval fortress adjacent to Green Square said in English, "Family members talk but don't fight each other." Another urged the Al Jazeera and BBC TV networks not to "spread news that reflect others' wishful thinking."
The fighting across Libya came as international concern deepened.
Pentagon spokesman Col. Dave Lapan said the U.S. was moving military forces nearer to Libya, but he declined to provide details. Other officials said the amphibious assault ship Kearsarge and its contingent of Marines were being sent to the Mediterranean from the Red Sea. They said there was no scenario under consideration in which troops would go ashore, except as part of a humanitarian mission.
David S. Cohen, the Treasury Department's acting undersecretary for terrorism and financial intelligence, said U.S. officials had not detected signs that the Libyans had been trying to remove any of the $30 billion that was frozen.
U.S. officials said many Libyan assets may be held in Persian Gulf countries, out of the reach of American and European regulators.
The European Union's foreign policy chief, Catherine Ashton, said: "What is going on — the massive violence against peaceful demonstrators — shocks our conscience. It should spring us into action."
Italy, Libya's closest European partner, cut ties with Kadafi's regime after Prime Minister Silvio Berlusconi was harshly criticized for being too tepid in his response to the government crackdown. Berlusconi's picture with the Libyan leader appears on Tripoli's airport road, and he once kissed Kadafi's hands at a meeting. Italian Foreign Minister Franco Frattini told reporters Monday that Italy had established contact with the anti-Kadafi Libyan National Council in Benghazi, but he declined to elaborate "so as not to jeopardize people who have put their lives at risk," the Italian news agency ANSA reported.
But diplomats in Washington said there still could be useful contacts with Kadafi via Italian officials and business figures.
Following the lead of the United Nations, EU officials banned not just the sale of weapons, but of any equipment that could be "used for internal repression."
They announced that in addition to Kadafi, some members of his family and other officials would be denied entry. Assets belonging to Kadafi, five of his relatives and 20 other Libyans would be frozen, they said.
Separately, British Prime Minister David Cameron said his country would be working with other allies on a possible military no-fly zone over Libya. In recent days, officials also blocked nearly $1.5 billion in Libyan bank notes from leaving Britain.
"It is clear that this is an illegitimate regime that has lost the consent of its people," Cameron told lawmakers. "My message to Col. Kadafi is simple: Go now."
French Prime Minister Francois Fillon said his country was dispatching planes carrying doctors and medical supplies to Benghazi.
The United Nations warned of a worsening humanitarian crisis as refugees, many of them migrant workers, fled to Tunisia and Egypt.
Demand for the flights has created a crisis at Tripoli's airport, where travelers packed the terminal. Arab, African and Asian workers, most of them in low-paying jobs in the service and construction sectors, have taken refuge in a vast tent city set up in airport parking lots, with plastic tarps and blankets serving as shelters.
"Partners, not wage earners," said a slogan inside the airport terminal, a citation from Kadafi's political and philosophical treatise, the Green Book.
Times staff writers Jeffrey Fleishman in Cairo, Henry Chu in London, Raja Abdulrahim and David Zucchino in Port Brega, and Paul Richter and David S. Cloud in Washington contributed to this report.