Without using Disk Utility, we can easily make a bootable USB Pendrive from Linux iso images in Mac OSX. For this purpose, we will use a third-party application called UNetbootin. UNetbootin allows us to create bootable Live USB drives for Ubuntu, Fedora, and other Linux distributions from bootable iso images.
1. First Download and install UNetbootin in Mac : http://unetbootin.sourceforge.net/
2. Then, open the application and select the Linux Distribution name and iso image.
3. Then select your USB drive in which you want to install the Linux Distribution and click "ok".