Safari is supposed to be compatible.
I tried just now with Safari 6.1.4 and Firefox 30.0 on MacOS 10.8.5.
In Firefox I could rotate the graphic but in Safari it was inert.
In case it makes a difference, my example input was
Plot3D[ Sin[x*y],{x,0,3},{y,0,4}, ColorFunction->"Rainbow"]
I will report it to cloud developers. I should not predict how long to get a correction in place.