Can I fix error 0xc0000225 without reinstalling Windows?

Depending on the method used, certain things can change in the progress:

The partition details: Use active in diskpart to make the partition activate again.

The boot sector: The bootsect tool can be used to restore the boot sector. (eg. bootsect /nt60 C:)

The partition UUID: By changing the partition position and/or size, the UUID changes; thus the inaccessible UUID stored in the BCD mismatches your partition's UUID. To fix this, remove and rebuild the BCD like this:

bcdedit /export C:\boot\bcd.backup
ren C:\boot\bcd C:\boot\bcd.old
bootrec /rebuildbcd

You might have caused the problem by reducing the Windows partition too much.

Windows has some unmovable files that a third-party product might decide to move. You should in the future use the Windows Disk Manager to resize its partitions, as it will not break the disk. It is also a good idea to first turn off and empty the Recycle Bin, disable the Paging file as well as hibernation, in order to minimize the number of special Windows files, and also run a defragmenter that compacts all files toward the beginning of the disk.

That said, you could do Repair Install to Fix Windows 7. This mild form of installation will fix your currently installed Windows 7 and preserve your user accounts, data, programs, and system drivers. The linked article describes the process in detail with screenshots. You might have to deal afterward with some destruction to the GRUB2 boot sector.

If Repair Install does not work, then Gparted had destroyed your Windows partition. I hope you have backup in this case, as otherwise you might have to resort to Data Recovery Utilities.