1. When you boot with your Win 7 OS installation DVD (or with the Win 7 OS Windows USB Media Tool flash drive) connected, access the boot menu during the boot process. You need to press the appropriate F key on your keyboard too access the boot menu. (It's also possible a key other than a F key will be the appropriate key). The appropriate key depends upon your motherboard's designation. If you don't know the appropriate key consult your motherboard's documentation (or try each F key in turn). Capiche?
2. When the boot menu appears the connected installation media will be listed as a SATA device and ALSO a UEFI device. Click on the UEFI device designation so that the system will boot to the UEFI interface.
3. You should then be able to install the OS onto your GPT-partitioned interface. The error message you indicated should not appear.
An addendum to my post...
If you're using a flash drive (a USB Media Tool containing the OS setup files) as the installation media, the boot menu will list the flash drive as a USB device as well as a UEFI device. Select the UEFI device as previously indicated.