That depends on what is in the ISO. If it is a dvd video, then yes, this can be compressed to fit a dvd-r disk. DVDShrink can open an ISO of a dvd video and compress it for you. (Control I in DVDShrink to locate the ISO)
If it is something else, you'll have to give us more information on what you have.
What size is the ISO? If it is smaller than 7.9gb, you can burn it to a double layer dvd. Use Verbatim brand DL disks if you choose this option...do not substitute another brand. Burn to the disk using a free burning program called ImgBurn.