The attack, which was claimed by the Islamic State group, involved bombings, gunfire and hostage-taking that wreaked havoc in eastern Baghdad.
"The intelligence effort was able to arrest the terrorist criminal gang that bombed Baghdad Jadida," a statement from Abadi's office quoted him as saying, referring to the area where the attack took place.
The statement did not provide further details on the intelligence operation or specify what role those arrested played in the attack.
IS overran large areas north and west of Baghdad in June 2014, but Iraqi security forces have since dealt the jihadists significant losses.
It still holds major areas in western Iraq, and also carries out frequent attacks in Baghdad and elsewhere.