Prices on the Kuwait Stock Exchange fell by 6 per cent while the largest Arab stock market in Saudi Arabia shed more than 3.5 per cent, nearly two hours before closing time.
The Dubai Financial Market index closed at 2,549.61 points led by Emaar Properties, the developer that built Dubai's Burj Khalifa, which fell by 8.36 per cent.
Saudi financial expert Bishr Bakhit said that "the reason of the drop is the agitation about Syria".
Kerry said the US was still examining evidence of the use of chemical weapons in Syria but left no doubt that Bashar al-Assad's regime would be blamed.