Q:

Trigger build only on pushes to master

I am using Jenkins with the Github Plugin I have integrated it  using GitHub's webhooks and it works like a charm, except that builds get triggered everytime something is pushed to the repository.
Is there a way to limit builds only when a change to the remote branch master has been made?

A:

Action Plan

Open the Jenkins job Configuration
Go to the section Source Code Managment
In the Git section

For the field Branches to build add the value */master

This tells this Jenkins Job, to only execute the job, when something is pushed to the branch master.
Figure: Shows the configuration, for building only branch master.

