The United States is moving warships and aircraft carriers closer to Libya, although military analysts say intervention through force is unlikely.
The British government meanwhile says it will work towards a no-fly zone over Libya.
On Monday the US met with NATO partners and other foreign governments to discuss military options.
President Barack Obama also met with UN Secretary General Ban Ki-moon, who expressed frustration with Gaddafi.
“He, (referring to Libyan leader Moammar Gaddafi), has lost his legitimacy when he declared war on his people. This is again a totally unacceptable situation. I hope, I sincerely hope and urge him to listen to the people’s call,” said Ban.
Colonel Gaddafi has come under increasing pressure from the international community since a unanimous resolution imposing sanctions on he and his closest aides, was passed by the United Nations last week.