You can add an artifact approval process by using Artifactory User Plugins. For example, we have a plugin, available HERE, that prevents the download of all artifacts with the following property:
approver.status set to rejected
You can edit this plugin to implement your own logic.
Another option is to use two repositories – one for approved artifacts and the other for unapproved ones. You can create an approved repository into which artifacts copied from one or another location could be moved there. Thereafter, you can assign read and any other permissions to the users who need access to those artifacts. Your unapproved repository would restrict permissions to these users.