Hi,
If you are 100% sure that it's not a malicious file then you can refer following articles.
How to Create Exceptions or Exclusions for Tamper Protection Alerts that have already been logged
http://www.symantec.com/business/support/index?page=content&id=TECH92553&locale=en_US
Configuring a centralized exception for a detected process
http://www.symantec.com/docs/HOWTO27305
OR
Submit it to Symantec response team to determine the next course of action.
http://www.symantec.com/security_response/submitsamples.jsp
Symantec Security Response usually takes half a day to a day to provide a response. In the interim, you can try these sites for a quick analysis because it's automated response: Own by Symantec only.
http://www.virustotal.com/
http://www.threatexpert.com/submit.aspx