When I use this in my listener class:

	@EventHandler(priority = EventPriority.HIGHEST)
	public void onMinecartEnter(VehicleEnterEvent event) {
		try {
			if (event.getEntered().getWorld().equals(this.gameMode.getMap().getWorld())) {
				event.setCancelled(true);
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}

I get teleported to my current location with a slightly higher Y, literally as if I was trying to enter the minecart but then got denied from it (but actually, it should just make you stay in your previous location that you were at when you tried right clicking the minecart).