It is possible to block specific applications running from removable media... but it is not possible to prevent copying the data from removable media to local disk you may have to permanently block removable media. There is a policy to make removable media as read only.

  create a application and device control policy for blocking the application you want and exclude all other except removable media.  This will block specific application running from removable media.

  
  REF:
http://service1.symantec.com/SUPPORT/ent-security....
http://service1.symantec.com/support/ent-security....

How to prevent programs from running by blocking the file extension types from removable drives.
http://service1.symantec.com/support/ent-security....
If no can you became more specific (What exactly you want to block from USB drives) 

It is also possible to block all USB drives other than you
specified

For more info refer the below doc

How to block USB Thumb Drives and USB Hard Drives, but allow
specific USB Drives in the Application and Device Control Policy in Symantec
Endpoint Protection.

http://service1.symantec.com/SUPPORT/ent-security....

@aravindkm - i think the above link isn't working

Hope this works

How to block USB Thumb Drives and USB Hard Drives, but allow
specific USB Drives in the Application and Device Control Policy in Symantec
Endpoint Protection

http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/b54beb2f46268ccc882574e80052960f?OpenDocument

 @Acretian the link what I posted is working for me I also checked it in colleagues pc there also it is working

How to prevent copying certain files like *.AVI or *.JPG through USB port.
Best Reagards
Ebey Samuel
HEISCO, Kuwait

You cannot denay copying to harddrives throuh SEPM policies..
But it is possible tomake your usb storedevices as read-only. So you  have to think in a different way to achive .
You can refer the earlier posts

You can also refer below links also

http://service1.symantec.com/SUPPORT/ent-security.nsf/2326c6a13572aeb788257363002b62aa/7049d06ba3c9e86f802573620054d9c2?OpenDocument

http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/afefa878c528d1ed882575520076cd16?OpenDocument

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007092616264848

with the help of this document you may block certain
applications like media player

http://service1.symantec.com/support/ent-security.nsf/docid/2009031809381448

with the help of this document you may allow only certain
usb drives in your organisation
You can also refer https://www-secure.symantec.com/connect/forums/dis...
 

Sorry for the wrong information because of my lack of knowledge
refer the link below 
Block copy and execution of specific files from an USB.
Some small modification may be required to match your scenario..