Updated 3:04 p.m. Eastern Time
President Obama said that Libyan leader Muammar Qaddafi must immediately comply with the demands of the international community and stop attacking his own people - and that a failure to comply will be met with military action.
The president said Qaddafi must stop his troops from advancing on Benghazi, pull them back from key areas of the country, allow for humanitarian assistance to reach Libyans, and make sure his people have access to water, gas and electricity.
"Let me be clear, these terms are not negotiable," said Mr. Obama. "These terms are not subject to negotiation. If Qaddafi does not comply with the resolution, the international community will impose consequences. The resolution will be enforced through military action."
The United Nations Security Council voted Thursday to authorize "all necessary measures" to keep Qaddafi's government from attacking the Libyan people, including the creation of a no-fly zone. The Libyan government declared a cease-fire following that vote, but Secretary of State Hillary Clinton , saying, "we would have to see actions on the ground, and that is not yet at all clear."
The Libyan Transitional National Council, which has spoken for the rebels, said Friday that the cease-fire is being breached and demanded immediate military action against Qaddafi.
Mr. Obama said that the United States would not lead any military action against Qaddafi but rather act in concert with the international community, and he said the United States "is not going to deploy ground troops into Libya. And we are not going to use force to go beyond a well-defined goal [of protecting civilians]."
Though U.S. officials say Qaddafi must ultimately step down, the president insisted that regime change in Libya and elsewhere in the Arab world "will not and cannot" be imposed from abroad.
The president said there is no decision that he considers more carefully than sending American troops into combat, particularly with two wars already raging. But, he said, America "will not stand idly by in the face of actions that undermine global peace and security."
"I've taken this decision with the confidence that action is necessary and that we will not be acting alone," he said. "Our goal is focused. Our cause is just, and our coalition is strong."
The president said Libyan protesters were "met with an iron fist" when they demanded accountable government universal rights, even as members of the government and others aligned themselves with the protesters.
(At left, CBS News' Harry Smith and CBS News national security correspondent David Martin discuss what kinds of consequences Qaddafi could face if he does not comply with the U.N. Security Council's demands.)
"Muammar Qaddafi clearly lost the confidence of his own people and the legitimacy to lead," he said. "Instead of respecting the rights of his own people, Qaddafi chose the path of brutal suppression. Innocent civilians were beaten, imprisoned and in some cases killed. Peaceful protests were forcefully put down. Hospitals were attacked and patients disappeared."
"There should be no doubt about his intentions because he, himself, has made them clear," added the president. "For decades he's demonstrated a willingness to use brute force through his sponsorship of terrorism against the American people as well as others and through the killings that he has carried out within his own borders."
The president said the United States and international community moved swiftly in response, culminating in Thursday's vote. He also made the case for action on the part of the United States and its allies.
"Here is why this matters to us," he said. "Left unchecked we have every reason to believe that Qaddafi would commit atrocities against his people. Many thousands could die. A humanitarian crisis would ensue. The entire region could be destabilized, endangering many of our allies and partners. The calls of the Libyan people for help would go unanswered. The democratic values that we stand for would be overrun. Moreover, the words of the international community would be rendered hollow."
"The United States did not seek this outcome," he added. "Our decisions have been driven by Qaddafi's refusal to respect the rights of his people and the potential for mass murder of innocent civilians."
The comments followed a meeting between the president and a group of Congressional leaders from both parties. Rep. Mike Rogers, the Michigan Republican who chairs the House intelligence committee, told CBS News the meeting was serious in tone. He said the United States would play a supporting role in any possible military actions led by the British, the French and Arab League countries.
Mr. Obama did not specify in his comments when military action would begin if Qaddafi does not comply.