A ceasefire to end the bloodshed in the region "must be lasting, permanent and sustainable," said a declaration released after the five-hour conference.
But despite the determined language, the pledge fell far short of meeting United Nations Secretary General Kofi Annan's plea for an "immediate cessation of hostilities" to stop the killing, with nearly 400 people dead in Lebanon, mostly civilians.
US Secretary of State Condoleezza Rice resisted persistent calls from allies for an immediate ceasefire, saying root causes, including the disarming and disbanding of Hezbollah, must be addressed first.
The calls were led by war-battered Lebanon and Arab states, backed by European allies such as France and Russia.
"We are all agreed that we want most urgently to end the violence on a basis that this time will be sustainable. Because unfortunately this is a region that has had too many broken ceasefires," Ms Rice told a news conference.
The lack of endorsement for an immediate ceasefire left a riled Lebanese Prime Minister Fuad Siniora asking if his people were "children of a lesser God".
"We are being pounded day by day, and scores of people are dying every day," Mr Siniora said, flanked by Ms Rice and Mr Annan.
"Can the international community continue to stand by while such callous retribution by the state of Israel is inflicted upon us?" he asked.
Secretary Rice insisted the "way forward" was based on UN resolution 1559, which calls for the disarming and disbanding of all militias, including Hezbollah, and for the Lebanese government to assert its authority over all its territory. Much of southern Lebanon is controlled by Hezbollah.
Talks to continue
To that effect, Ms Rice told journalists multilateral talks would occur "over the next several days" to discuss the establishment of an international security force for southern Lebanon.
"The mandate of the security force will be discussed over the next several days. We have asked for urgent meetings to take place so that a force can be put together."
Ms Rice warned Syria and Iran, long seen as Hezbollah's puppet-masters, that it was time for those countries to "make a choice" about their role in Middle East peace.
"Syria has a responsibility," Ms Rice said. "And we are deeply concerned, as we have said, about the role of Iran. It is high time that people make a choice."
British Foreign Secretary Margaret Beckett said later she expected the main points of the Rome declaration to be put before the UN Security Council "next week".
The 15 nations gathered in Rome also called on Israel to exercise "utmost restraint" while welcoming Israel's decision to let aid into Lebanon including aid flights to Beirut airport.
French Foreign Minister Philippe Douste-Blazy lamented the failure to agree on an immediate ceasefire.
"There was no agreement and we agreed to work in a very urgent way for a cessation of hostilities. We would have liked the word 'immediate' more than the word 'urgent' in the text," he said.
A diplomat in the meeting said on condition of anonymity that the dispute about ceasefire language alone took 45 minutes of the five-hour talks.
Mr Siniora kept interjecting, saying that people were dying, according to the diplomat. "Rice told everyone they needed to get a 'reality check' that there was not going to be a ceasefire immediately."
Ms Beckett, explaining later in an interview with Sky News why no ceasefire was achieved, said "even if we could get a ceasefire half an hour ago we would be back to hostilities within days."
"We stand the best chance of getting a ceasefire if we have all the right conditions in place over the next few days. We're talking days not weeks," she added.
International force
A key part of a lasting ceasefire is the establishment of a buffer force, but there are differences over its composition and the conditions under which it should be deployed.
Diplomatic sources said Mr Annan raised the need to have a separate international force on the ground as soon as possible -- not the long-term stabilisation force -- to enable humanitarian aid to get through.
Mr Annan, a trenchant but ultimately frustrated campaigner for an immediate ceasefire, had urged the conference to "send a strong message and speak with one voice".
"A temporary cessation of hostilities would offer crucial hours and days for essential humanitarian tasks," he said.
As well as Italy's Foreign Minister Massimo D'Alema, US
Secretary of State Condoleezza Rice and United Nations Secretary General Kofi Annan, the other countries represented were Britain, Canada, Cyprus, Egypt, France, Germany, Greece, Jordan, Lebanon, Russia, Saudi Arabia, Spain and Turkey. The World Bank and European Union were also present as was the Vatican in an observer role.