Foreign ministers of the Friends of Syria group, who are meeting in Qatar, have agreed to provide urgent support to rebels who are fighting President Bashar al-Assad.
Qatar's PM Sheikh Hamad bin Jassim bin Jaber al-Thani said "providing arms may be the only means of achieving peace".
The group also condemned the Syrian government for its use of Iranian and Hezbollah fighters.
More than 90,000 people have died in more than two years of conflict.
The Syrian government says it is fighting foreign-backed "terrorists".