You are looking for the standalone definitions updater, Intelligent Updater, for the Symantec Endpoint Protection (SEP) client for Mac 14.x.
The file you use depends on the version of Symantec Endpoint Protection that you use.
All of these files are zipped Mac installer packages (.pkg). Transfer the file unzipped to the Mac system, unzip it there, and double-click on the pkg file to run it. Unzipping it elsewhere then copying the pkg to the Mac can result in installer errors.
Currently SEP 14.3 RU2 and newer is not supported.