Speaking ahead of a meeting of the "Friends of Syria" group of nations on Saturday, Louay Meqdad, a spokesman for the Free Syrian Army, declined to give details of the weapons to reporters.
He said they had not come from the US.
The US announced last week that it would provide Syrian rebels with "direct military aid".
The decision followed what the White House said was clear evidence of small-scale chemical weapon attacks by the government.
President Barack Obama said that the use of such weapons crossed a "red line", triggering the change in policy towards the Syrian conflict.
Mr Meqdad told AFP that the Free Syrian Army had begun distributing the weapons on the front lines.
"We've received quantities of new types of weapons, including some that we asked for and that we believe will change the course of the battle on the ground.
"The weapons will be used for one objective, which is to fight the regime of Bashar al-Assad," he said.
Ministers from the "Friends of Syria" countries, which back the uprising against President Assad, are due to meet in the Qatari capital, Doha.
The group includes the US, Britain, France and Germany as well as Saudi Arabia, Turkey, Egypt and Jordan.
A spokesperson for the US state department said that Saturday's meeting would be focused on how the international community could support the Syrian opposition to make it "more cohesive, more representative and more credible inside Syria".
Meanwhile, Russian President Vladimir Putin again warned the West against arming the Syrian opposition.
Speaking in St Petersburg during a visit by German Chancellor Angela Merkel, Mr Putin said he feared a "political void" would be filled by "terrorist organisations" if Mr Assad were to leave power.
Meanwhile the United Nations children's agency Unicef has warned that soaring summer temperatures are adding to the health dangers threatening the four million children it says are affected by the conflict in Syria.
More than 90,000 people have lost their lives in the fighting, and many more have fled the country.
Syrian rebels say they have received new weapons that could lead to "changes" in the fighting in the country's civil war.