Clinton met with Italian Foreign Minister Franco Frattini ahead of the meeting on Libya, which focused on financially helping the rebels, who say they need $1.5 billion in the coming months just for food, medical and other basic supplies.
The meeting of 22 nations and some international organizations also included the NATO chief, the Arab League, and the leader of Libya's opposition council, Mustafa Abdel-Jalil, who used to be Gadhafi's justice minister.
Clinton said the meeting will seek "the most effective ways to deliver financial assistance" and other support "with urgency." "Everyone is always impatient. We expect things to be done immediately in our very fast world," Clinton said.
Clinton said she would be formally presenting the U.S. pledge to provide $25 million in surplus, nonlethal goods to support and protect the rebels.
Italy, conference co-host Qatar and France have given diplomatic recognition to the rebels, who are based in the western Libyan city of Benghazi. Frattini opened the four-hour closed session with a call for other nations to do so as well.
"This will help strengthen our Benghazi partners and increase the Gadhafi's regime sense of isolation," the minister said.
With NATO chief Anders Fogh Rasmussen among the participants, Frattini said "military pressure is not a goal per se but it is a very important tool."
Since the uprising against Gadhafi broke out in mid-February, the two sides have largely been locked in a stalemate. A U.S. and now NATO-led bombing campaign, launched in mid-March, has kept Gadhafi's forces from advancing to the east, but has failed to give the rebels a clear battlefield advantage.
NATO said earlier this week its warplanes will keep up the pressure on Gadhafi's regime as long as it takes to end the violence in Libya.
Frattini's remarks reflected increasing realization by NATO mission participants that air strikes and other military action alone won't do the job of ending Gadhafi's relentless assault on his people, and that funding the opposition as well as working for the Libyan leader's ouster could be the key to success.
French Foreign Minister Alain Juppe, whose country is at the forefront of the military campaign in Libya, has said the military intervention must end "as rapidly as possible," and warned that sending in international ground troops would set the stage for a "quagmire."
And Frattini has said while it was impossible to set a date for an end to NATO's military operation the "political goal is for military action to cease as soon as possible."
Frattini urged the U.N. Security Council sanctions committee to figure out how the rebels can request unfreezing of billions of dollars in Libyan assets to be used for humanitarian purposes.
The rebels have also called for weapons to be able to defend themselves from Gadhafi's better-equipped forces.
Rebel spokesman Abdul Hafid Ghaug, said in Benghazi that no country had sent the arms that the rebel forces say they desperately need. "Up to this point we have not received any commitments (for weapons) from any friendly nation," he said.
British officials said the Rome meeting would also seek to impose new restrictions on arms smuggling and mercenaries operating within Libya, call for renewed action to cut off Libya's state television service and try to restrict Gadhafi's exports of crude oil and his ability to import refined oil products.
It was the second meeting of the group after a gathering in Doha, Qatar, last month.