Roma were sent out 4-1 on aggregate after a 3-0 defeat at the Stadio Olimpico, leaving Rudi Garcia's men facing up to a season without silverware.
Having exited the Coppa Italia and with 14 points between themselves and Serie A leaders Juventus, Sabatini felt the club's inability to sign in-form Fiorentina loan star Mohamed Salah has been detrimental to their recent form.
Sabatini - who instead opted for Seydou Doumbia from CSKA Moscow - told Sport Mediaset: "I made a mistake in January.
"The team needed strengthening in attack and the choices I made haven't had the desired effect so far.
"I have to take the blame for those mistakes because they have weighed on the team and the coach.
"The blame lies exclusively at my door, but I'll analyse everything further down the line because it's easy to hold your hands up now.
"Salah is a player to be regretted and another mistake that I made.
"It is easy to accuse yourself without secondary effects, but what I say now will still be valid in future.
"Nobody is abandoning ship, least of all myself. Quitting now would be like escaping and that's not something I'm used to doing. I have to think about the consequences that have led us to dropping points."
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