We do not have an Approval process, but we do have access options from the Settings of an event, to only allow those who have access to the event to buy tickets. To provide selective access, follow the steps below:
Go to Design Event Campaign -> Click Settings -> go to Campaign Access -> choose the option that meets your criteria:
Public: Allow access to everyone.
Public: Allow view access to everyone; gate access to participation forms. (Allow users to participate by using either an Access Code or Tikkl email invitations)
Private: Allow access to anyone with URL.
Private: Allow access only to invitees via Tikkl email invitations.
To deny registration of an attendee, admin can cancel the ticket and refund the money back to attendee.