Hey Joy,
Whenever an asset is dragged onto the page, the "DAM Update Asset" workflow launcher is specifically triggered.
With workflow launchers, you can add conditional logic to say whether the resource will be triggered against the workflow or not.
You can achieve this by adding something like:
jcr:createdBy=admin
Documentation on how to add a condition to Workflow Launchers can be found here -> https://helpx.adobe.com/uk/experience-manager/kb/ConditionsInWorkflowLauncher.html
I hope this helps.