Regime's internal wars
The simple truth is that Iran's supreme leader Khamenei is consolidating his power base. He is tired of playing 'democracy' and has decided to do away with the fake democratic aspect of the regime such as elections. Khamenei is using the revolutionary guards to politically remove other factions and elements from his path.
I get dizzy (and sometime I laugh) when I see western pundits trying to figure this "puzzle" that is the Iranian regime. This is no puzzle, dudes. Khamenei runs the show, and has been running it since his predecessor died in 1989.