Delegates from more than 70 countries attending the inaugural "Friends of Syria" meeting in Tunisia have issued a declaration calling for an immediate end to the violence in Syria and endorsing the main opposition umbrella group, the Syrian National Council (SNC), as a "credible" voice of opposition, al Jazeera television reported.
The conference fell short of declaring SNC a government-in-waiting.
Delegates also called on President Bashar al-Assad to let in humanitarian aid and vowed to ratchet up sanctions against the regime.
"[Friends of Syria] demanded that the Syrian regime immediately permit humanitarian agencies to deliver vital relief goods and services to civilians affected by the violence," the declaration said.
The meeting came as the Syrian goverment resumed its bombardment of the opposition stronghold of Homs. The International Committee of the Red Cross (ICRC) has said it evacuated 27 people from Bab Amr, Homs' most embattled district, on Friday and that talks are being held to evacuate more on Saturday.
"The ICRC will continue its discussions and negotiations with the Syrian authorities and members of the opposition so we are able to pursue these rounds of evacuations," the group said in a statement.
Government forces killed 103 people across the country on Friday, the activist group Local Co-ordination Committees said.
Rights groups say the 11-month uprising against President Bashar al-Assad has claimed more than 7,000 lives.
The government says around 2,000 members of its security forces have been killed combating "armed gangs and terrorists."
At the White House on Friday, President Barack Obama said the U.S. could not be a "bystander" and vowed to consider "every tool available" to "prevent the killing of innocents in Syria."
"It is time for that regime to move on. And it is time to stop the killing of Syrian citizens by their own government," Obama said.
At the Tunis meeting, U.S. Secretary of State Hillary Clinton said the violence in Syria was an "affront to the international community" and that President Assad and his backers will "bear responsibility" for what she described as a "humanitarian catastrophe."
She also strongly criticized Russia and China which both refused to attend the conference and earlier vetoed tough action on Syria in the UN.
"They are setting themselves not only against the Syrian people but also the entire Arab awakening," Clinton said.
"It's quite distressing to see permanent members of the Security Council using their veto when people are being murdered - women, children, brave young men - houses are being destroyed."
"It is just despicable and I ask whose side are they on? They are clearly not on the side of the Syrian people," she said.