The announcement that the Nusra Front had merged with the Iraqi terrorist group drew expressions of "surprise and dismay" from the Syrian Islamic Liberation Front, The New York Times reported Friday.
"We won't be doing our population, and our nation, any service if we pledge our allegiance to those who don't know a thing about our reality," the coalition said in a statement.
On Tuesday, Abu Bakr al-Baghdadi, the leader of the Iraqi al-Qaida group, announced the merger of the two organizations. He said half the group's budget would be dedicated to toppling Syrian President Bashar Assad.
The Nusra fighters are admired for their military skill, but moderate groups have been worried by Nusra's disregard for civilian casualties and its call for a strict Islamic state.
Members of the coalition are worried the al-Qaida announcement will bolster Assad's contention the opposition to his government is fueled by foreign sources with ties to terrorists.
The leader of the main Syrian opposition group, the National Coalition of Syrian Opposition and Revolutionary Forces, immediately denounced the combination of the extremist groups.
"The bottom line: the ideology of al Qaida doesn't suit us, and the revolutionaries in Syria must take a clear stance on this matter," said Moaz al-Khatib on his Facebook page.