Judge M L Tahaliyani said Kasab's statement before the court was "broadly speaking not a confession, but an admission of guilt."
The judge's observation came after Kasab concluded his version of events related to the November 26 terror strikes.
In a dramatic turn of events, Kasab confessed on Monday to his involvement in the terror strikes at the Chhatrapati Shivaji Terminus and other locations in south Mumbai, apart from giving a detailed description of his training under the Lashkar-e-Tayiba in Pakistan.
Kasab was free to plead guilty at any point of time during the course of the trial, the judge observed. The court would need to verify whether Kasab was genuinely pleading his guilt as there were many charges against him, Judge Tahaliyani said.
The court could then accept or reject Kasab's statement or accept his plea and continue with the trial, the judge said.
Kasab, the only terrorist who was caught alive during the Mumbai attacks, had recorded a confession before a magistrate, but later withdrew it, alleging that it was obtained through coercion by the police.
He had earlier pleaded not guilty to the charges framed against him.