A summit of more than 70 nations has declared support for an immediate ceasefire in Syria.
In its chairman's conclusions to the meeting, released by the Foreign Office, the group called on Syrian President Bashar al-Assad to "immediately cease all violence" and "committed to take steps to apply and enforce restrictions and sanctions on the regime".
However the Syrian National Council opposition group, recognised today by Foreign Secretary William Hague as "a legitimate representative of the Syrian people", said the talks were a disappointment.
It called for a stronger commitment to ensuring humanitarian aid reached the country, and asked for arms to reach opposition fighters.
The SNC said in its demands presented at Tunis, it said: "If the regime fails to accept the terms of the political initiative outlined by the Arab League and end violence against citizens, the Friends of Syria should not constrain individual countries from aiding the Syrian opposition by means of military advisers, training and provision of arms to defend themselves."
The summit stopped well short of agreeing to military intervention in its final declaration, released on Friday evening.
In its statement the group "expressed strong condemnation of the Syrian regime’s ongoing, widespread, and systematic human rights violations, including: the indiscriminate use of force against civilians".
It said Assad's atrocities "amount in some cases to crimes against humanity" and "viewed the regime’s use of heavy artillery and tanks to attack residential areas of cities and towns as particularly reprehensible".
The group called for the formation of a national unity government and transparent and free elections, and "noted that the Syrian government's effort to impose unilaterally a set of political steps labeled as reforms would not resolve the crisis".
On the humanitarian crisis in the country, the declaration "reiterated the need urgently to address humanitarian needs" and "called on the Syrian government immediately to cease all violence and to allow free and unimpeded access by the UN and humanitarian agencies to carry out a full assessment of needs".
At the meeting some Arab nations including Saudi Arabia and Qatar pushed for a more aggressive strategy, and Saud al-Faisal, the Saudi foreign minister, said he would support arming the opposition.
Moncef Marzouki, the Tunisian president, also backed the peacekeeping force plan and suggested Assad might be granted immunity from prosecution if he left office.
"A political solution must be found," he said. "Such as granting the Syrian president, his family and members of his regime judicial immunity and a place to seek refuge."
Speaking after the conference US Secretary of State Hillary Clinton said she was sure President Assad would eventually lose power, and that only a genuine transition to democracy would free the country of violence.
"It is a difficult dilemma to face a Syrian government that is intent on killing," she said. "We must stay on the path of peace."
Foreign Secretary William Hague said he was confident the European Union would agree further sanctions to tighten the "diplomatic and economic stranglehold" on the Syrian regime, and that it was vital not to abandon the Syrian people in their "darkest hour."
Before the conference he told reporters the Syrian government is now a "criminal regime".
Hague said that he now recognised the opposition Syrian National Council (SNC) as "a legitimate representative of the Syrian people".
“I think we have seen enough in the last few weeks to know that the Assad regime will go down in history as a criminal regime.
"The United Kingdom will continue our work to help document the crimes that are taking place so that one day those responsible for them will have to answer for their actions."
The foreign secretary also called on China and Russia, who have consistently voted against condemnation of Syrian President Bashar al-Assad' regime in the United Nations, to change their position.
"I hope those countries will take note of this strength of international feeling and support that we’re seeing here in Tunisia with more than sixty countries coming together," he told reporters. "Because it means that they are increasingly isolated in their view."
"It’s very important for Moscow and Beijing to a re-evaluate their position".
Neither Russia or China attended the 70-nation Friends of Syria meeting organised by the Arab League.
But Russia independently issued a statement calling for an immediate ceasefire in the country on both sides. It also asked other countries to condemn the actions of the armed opposition as well as the government.
Meanwhile the Red Cross said it had begun evacuating wounded people from the embattled city of Homs.
Violence continued across the country, however, and videos posted by citizen journalists showed a high presence of Syrian forces in Daraa, close to the Jordanian border, including snipers posted on the top of buildings.
Avaaz citizen journalist 'Abu Hanin' reported via Skype: "We stopped trying to count the number of those killed and wounded. It is very difficult to determine an exact figure, we cannot get to the places of the bombing, we do not know if people were able to escape from the destroyed buildings or if they are under the rubble."
Around 8,000 people have died since the start of anti-government protesters in March 2011, activists have said.
The Syrian government insists the violence is mainly the result of "armed terrorist groups".