Revoke save event on save button click

I’m displaying a dialog box for confirmation and I display it before_save of Actual Form.
But when I Click on Save button of Actual form, look What actually happened.

-> Its default Save function called automatically and Save button turn to submit button,
-> It displayed a Dialog box for Conformation.

But I want to call its default save function on my save button which I placed at Dialog Box.

Please help me out to revoke its default save function and let it call on my on save button which I placed on Dialog Box.

here are screenshots.
before click on save button.

After Click on save button.