Paris (CNN) -- U.S., European and Arab leaders delivered a strong warning to Libyan leader Moammar Gadhafi on Saturday, saying he must stop attacking his own people or else face international military action.
The warning, announced by French President Nicolas Sarkozy at the end of a last-minute meeting in Paris, came as Sarkozy revealed French fighter jets were already flying over rebel-held areas of Libya to protect the population.
"If there is not an immediate cease-fire and withdrawal of the forces that have been attacking civilian populations in the last few weeks, our countries will have recourse to military means," Sarkozy said, adding that all participants at the meeting endorsed the warning.
French planes fired on a Libyan military vehicle Saturday evening, according to the French Defense Ministry.
Participants at the meeting in Paris agreed on an urgent need to act. They agreed to use "all necessary means, in particular, military means" to enforce a United Nations resolution authorizing the use of force against Libya, Sarkozy said.
Gadhafi, however, "has totally ignored this warning," Sarkozy said.
Sarkozy called it the "murderous madness" of a regime that has "forfeited all its legitimacy."
At the same time he spoke, Sarkozy said the French air force is opposing any aggression by Gadhafi's forces against the population of rebel-held Benghazi.
"As of now, our aircraft are preventing planes from attacking the town," Sarkozy said. "Other French aircraft are ready to intervene against tanks."
Sarkozy said enforcing the U.N. no-fly zone through military action is not in order to impose a specific outcome -- such as regime change -- but is instead "in the name of the universal conscience that will not endorse such crimes."
U.S. Secretary of State Hillary Clinton echoed that idea, saying the purpose of enforcing the U.N. resolution is "to protect civilians from their own government."
Sarkozy said Gadhafi still has a chance to "avoid the worst" if he complies "immediately and unreservedly" with the demands of the international community.
"The doors of diplomacy will open once again when the aggression stops," he said.
Sarkozy's comments came at the end of Saturday's meeting, which included delegations from the United States, Canada, European Union and Britain, along with Iraq, Morocco, the United Arab Emirates and the United Nations.
In a communique, leaders said they have a long-term commitment in the area.
"We assure the Libyan people of our determination to be at their side to help them realize their aspirations and build their future and institutions within a democratic framework," the statement said.
British Prime Minister David Cameron, who was at the meeting in Paris, said participants decided to make Gadhafi face the consequences of his actions.
"Colonel Gadhafi has made this happen," Cameron told the BBC. "He has lied to the international community. He has promised a cease-fire, he has broken that cease-fire, he continues to brutalize his own people, and so the time for action has come. It needs to be urgent."
As they met, participants were "aware of the news reports" coming out of Libya that show Libyan government forces moving toward Benghazi, a senior U.S. State Department official told reporters.
"Time is pressing," Herman Van Rompuy, president of the European Council, told the meeting Saturday. "Action is needed now to protect the population."
Clinton said Gadhafi's forces "face unambiguous terms" and that a cease-fire must be implemented immediately.
"That means all attacks against civilians must stop," she said after the Paris meeting. "Troops must stop advancing on Benghazi and pull back from Ajdabiya, Misrata and Zawiya. Water, electricity, and gas supplies must be turned on to all areas. Humanitarian assistance must be allowed to reach the people of Libya."
Italian Prime Minister Silvio Berlusconi, another participant at the meeting, proposed the use of the NATO base in Naples as a command center for allied action in Libya, a spokesman for the Italian leader said.
CNN's Elise Labott, Jill Dougherty and Hada Messia contributed to this report