This is actually a bug, however, there is a known solution.
First, edit your /etc/X11/Xresources/x11-common file:
sudo nano /etc/X11/Xresources/x11-common
Now, add this to or edit the file to include the following:
Xcursor.size: 22
Xcursor.theme: DMZ-Black
Known sizes are 8, 16, 22, 24, 32
Press CTRL + o and then press ENTER to save the file. Press CTRL + x to exit nano.
Log out and then log back in or restart your xsession to apply the changes.
Personally, I use Adwaita instead of DMZ-Black. Adwaita is a quite similar black cursor but has a different spinning icon for when the system is busy.
You can install it:
sudo apt-get install adwaita-icon-theme-full
Then, set the file like so:
Xcursor.size: 22
Xcursor.theme: Adwaita
source: bugs.launchpad.net
See this related answer for how to change the cursor size on certain applications.
Try unclutter.
The purpose of this program is to hide the pointer after the mouse has not moved for a while. Using it, you can make the pointer appear only when the user touches the screen, and disappear right after it. Maybe this was not exactly what you were aiming for, but it is much easier than your alternative.
To use it, first install it:
sudo apt-get install unclutter
then run it:
unclutter -idle 0.01 -root
The number in the above command is the number of seconds before the pointer disappears (in this case, 1/100 seconds).
Best Answer
This and this video tutorial might help you making cursor theme.
To change cursor theme, Go to software center and install Unity tweak tool. Open it, select cursors and select the cursor that you like.