You can create an udev rule to hide the partitions.
For Lubuntu 12.04
In this example I have two partition (NTFS).
WIN-NTFS1 and WIN-NTFS2

1) Search information about your partitions.
Open a Terminal and type:
In my case the result is:
/dev/sda1: UUID="c3338905-348b-47c8-bc55-f363bc487410" TYPE="ext4"
/dev/sda3: LABEL="WIN-NTFS1" UUID="1F297ED5220E41AA" TYPE="ntfs"
/dev/sda4: LABEL="WIN-NTFS2" UUID="4CFEB84C16B24904" TYPE="ntfs"
/dev/sda5: UUID="4b1b8aac-4ee7-42ed-8ed6-3ab7443ee607" TYPE="swap"
Write down the device information eg:(sda3), in my case:
/dev/sda3: LABEL="WIN-NTFS1" UUID="1F297ED5220E41AA" TYPE="ntfs"
/dev/sda4: LABEL="WIN-NTFS2" UUID="4CFEB84C16B24904" TYPE="ntfs"
2) Create the udev rule.
In the terminal window type:
sudo nano /etc/udev/rules.d/99-hide-ntfs-partitions.rules
Match the "KERNEL" key with you device and assign the "UDISKS" variable.
The content of the 99-hide-ntfs-partitions.rules file would be:
KERNEL=="sda3", ENV{UDISKS_PRESENTATION_HIDE}="1"
KERNEL=="sda4", ENV{UDISKS_PRESENTATION_HIDE}="1"
To save the changes in nano...
Ctrl+O, Enter and Ctrl+X.
3) Finally refresh the udev rules with:
The result is :

For Lubuntu 12.10 & 13.04.
The only difference is the name of the UDISKS variable.
It should be ENV{UDISKS_IGNORE} instead ENV{UDISKS_PRESENTATION_HIDE}
The content of the 99-hide-ntfs-partitions.rules file would be:
KERNEL=="sda3", ENV{UDISKS_IGNORE}="1"
KERNEL=="sda4", ENV{UDISKS_IGNORE}="1"
Hope it helps.