There were similar demonstrations in Toronto, Dublin and London

BBC News - Syria: Army in Deraa arrests 500 men 

Arab leaders pressed to break silence on Syria

Syria Steps Up Pace of Arrests; at Least 2434 Detained

Tens of thousands defy violent crackdown across Syria

I suspect Syrians  feel their honor is on the line.  Assad will find that scarring them silent is not going to be easy despite the fact that the world is too distracted to pay much attention to his victims.