This indicates that some server connected to the filer via iSCSI is sending SCSI bus resets (probably because the LUN doesn't respond quickly enough because of the high load). Try finding out which FC initiator/host is sending the resets ("fcp show initiator" and/or other fcp subcommands, look for the port ID given in the message)
Then, if you have the host, try finding out if there are any timeout values you can increase (disk timeouts, FC timeouts, SCSI timeouts). Or, even better, install the NetApp host utilities on that host that should fix the timeouts for you for the most common platforms/OS'es
-Michael