Show block only on node view page, not in node create or edit form
Use this in your block configurations page "Show block on specific pages" > "Show if the following PHP code returns TRUE"

if(arg(0) == 'node' &amp;&amp; is_numeric(arg(1)) &amp;&amp; ((arg(2) == "" || arg(2) == 'view'))) {
  return TRUE;
}


Hope this will help.

You will need to enable the core module PHP.