If you straight download the OVF from vSphere using the vSphere client, I'm not sure if that would be directly compatible as an import to vCloud 1.5. It's worth a try, just to see if it works.
possibly, use VMware converter to export the VM from vSphere to an OVF version with vHardware 8 or less (ensure compatibility with ESXi 5.0 or prior destinations).
Also, vCloud Director 1.5 isn't supported anymore ... so I'd possibly look at getting that updated.