Yes, the U.S. should have suspended non-lethal aid to Syrian rebels, because the United States is only giving the rebels the tools to hurt a great deal of people. The Syria situation is far too complicated for the United States to intervene effectively. The United States should not be using its wealth to help people hurt other people.
The United States does not fully understand the composition of the rebel groups comprising the resistance to the Assad regime in Syria. Accordingly, other than simple humanitarian aid, such as food, water and clothing, the United States should not be supplying military aid to the rebels. They could eventually use that aid against U.S. interests in the future.