Set the button type to something other than MS-DOS Batch and you won't see any DOS box when it's run.
Generally the MS-DOS Batch button type is only used when you're running command-line programs and you want to see their text output. If you just want to run a command with some arguments then the button can be one of the other types.
(You can also run MS-DOS Batch buttons without a window appearing by setting the run mode to Hide, but in this case you can avoid the DOS button type completely which is better.)