If you are using text() then you might want to try changing the horizontal or vertical alignment; see http://www.mathworks.com/help/matlab/ref/text-properties.html
If you are using text() and the alignment is not enough, then you will need to add an offset to your coordinates. What offset to use will require some thought that takes into account the various axes view properties such as camera target, and the DataAspect, and the [XYZ]Limit properties, so that after the projection due to the view is taken into account, the label becomes far enough away.
