The highest voted solution doesn't work for me. I am using version 6.5.4.
the Inno Setup keep generating the manifest with "asInvoker".

My solution is:

1, Use "Resource Hacker" to manually edit the file "SetupLdr.e32" from Inno Setup installation folder, usually it would be "C:\Program Files (x86)\Inno Setup 6" (make sure you have a backup), choose the "Manifest", change it from "asInvoker" to "requireAdministrator", compile and save, then override the file back.

2, Add the "DisablePrecompiledFileVerifications=setupldre32" under [Setup] Section, to avoid Inno compile issue(ask Inno to ignore it being changed outside).

3, rebuild.