The United States is providing Syrian rebels with 123 million dollars (£80 million) in new non-lethal aid that may include armour and other types of supplies that have not been part of the assistance package in the past.
US Secretary of State John Kerry said the additional money will double the non-lethal assistance to the Syrian opposition as well as increase humanitarian aid.
Speaking in Istanbul, Mr Kerry said the situation in Syria is at a critical moment and that the bloodshed needs to stop.
Foreign ministers from the main supporters of the rebels trying to topple the Syrian government are meeting in Istanbul over the weekend to increase pressure on Syrian President Bashar Assad to step down.
The United Nations estimates that the fighting in Syria has killed more than 70,000 people.
"The stakes in Syria couldn't be more clear: chemical weapons, the slaughter of people by ballistic missiles and other weapons of huge destruction, the potential of a whole country ... being torn apart into enclaves, the potential of sectarian violence," Mr Kerry said.
"This bloodshed needs to stop and that's what brought us here tonight on Saturday and a very early Sunday morning to talk about the possibilities for peace and transition."
In a joint statement, the foreign ministers said they welcomed the Syrian National Coalition's "firm rejection of extremism and its commitment not to use chemical weapons" and cited those commitments in agreeing to enhance and expand support for all coalition institutions.
The foreign ministers said they recognised the "need to change the balance of power on the ground" and, in looking at the current flow of military assistance, welcomed the additional pledges and commitments to further increase the support to the Supreme Military Council. The head of the council provided a military briefing during the meeting.
The Syrian National Coalition said the limited support, while appreciated, was not enough. "We call on the international community to be more forthcoming and unreserved to fulfil its responsibilities in extending support that is needed by the Syrian people."