Here are several options (none of them have been tested, so test and see which one works for you):
Option 1:
tell application "iTerm2" to activate
tell application "System Events" to tell process "iTerm2" to keystroke "h" using command down
Note: Keystroke may be replaced with m if you want iTerm2 to be minimized to the dock with the Genie effect.
Option 2:
tell application "Finder"
set visible of process "iTerm2" to false
end tell
Option 3:
tell application "System Events" to tell process "iTerm2" to set visible to false
Note: The process name may just be iTerm instead of iTerm2.
I opened iTerm on my Mac and then Activity Monitor,
and the Process Name that it shows is iTerm.
Please change accordingly if it does not work for you.
If you make the iTerm window the frontmost application
(Be careful you don't want to make the AppleScript window the frontmost application), try this script:
tell application "System Events"
set frontProcess to first process whose frontmost is true
set visible of frontProcess to false
end tell