Install VMware Fusion 5 from ISO image on my Mac
Generally speaking the Mac will treat an .ISO file the same as a .DMG file, at least in my experience...

So put the file on your Mac and double click on it and see what happens.

Failing that rename it to .DMG and try again.

It is quite possible that the .ISO file you have is the Windows version and has only the Windows installers on it (Setup.exe or Install.msi, etc.) but as counter intuitive these suggestions sound, they have worked for me and should at least allow you to open the .ISO and see what lies within.

And a commenter reminds me that there is no VMWare Fusion for the PC, rather it is called VMWare Workstation.