Create USB from ISO in Mac

List all disks

diskutil list

Output:
% diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macintosh HD            250.1 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           +249.8 GB   disk1
                                 Logical Volume on disk0s2
                                 B030DEDE-8859-44D3-89B7-9008D798490B
                                 Unencrypted
/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *16.0 GB    disk2
   1:                       0xEF                         9.2 MB     disk2s2

Write ISO to this USB drive

sudo dd if=/Users/flemieux/Downloads/livecd-centos-7-live-gnome-201406261459.iso of=/dev/disk2 bs=1m