This blogpost claims so. It states:
Another hot news from Arabic Facebook. Here is the summary
U.S. missile attack will damage not only Assad troops but also opposition forces! According to source in the Turkish General Staff, during the second phase of the operation in Syria, U.S. missiles will vanish militant training centres of “Al-Nusra Front” and “Islamic State of Iraq and Shama”. The U.S. will also destroy the control centres of the main radical opposition groups and this way the problem of Islamic extremists in Syria will be solved.
In another article I read that one Al Nusra unit had arrested someone for placing transponders that could make them a target for US bombings.
5 September 2013: Syrian Islamists believe they will be targets of US air strikes: Jihadists move personnel and weaponry ahead of expected intervention