Hi,
you should configure BPDU guard under etherchannel.
The command should be issued under the Port-channel interface.
The consequence of this action is that any possible Bpdu sent by netapp appliance will cause the port-channel to go down. You could try to bring the interface up manually or by the use of errdisable recovery functionality.
You should be aware though that some appliances sometimes loops back to the switch its own Bpdus(i do not know if netapp actually does it) so technically there could be a chance that after issuing the command you may see the port-channel going down.
In that case you should work on your appliance to stop the Bpdus to go out towards the switch.