Hezbollah's leader has said two Israeli soldiers held by his group will only be released if a Lebanese militant held by Israel for 27 years is also freed.
Nasrallah has said he did not expect to provoke war with Israel
Hassan Nasrallah said that any deal with Israel would have to include Samir Qantar, convicted of several murders after a cross-border raid in 1979.
The capture of two Israeli soldiers in July sparked a month-long conflict.
On al-Jazeera TV, he was also critical of UK PM Tony Blair, labelling him an "accomplice in the killing".
Sheikh Nasrallah had sharp words for the Lebanese Prime Minister, Fouad Siniora, who this week welcomed Mr Blair to Lebanon for the first time.
"Tony Blair is an accomplice in the killing. Why then do you bring him to my house and to my family and receive him warmly?
"Do they not have feelings?"
Discussing the prospects for a prisoner exchange, Sheikh Nasrallah explicitly denied Hezbollah would agree to any proposal that did not include Qantar.
Samir Qantar was captured during a cross-border raid into the northern Israeli town of Nahariya in 1979.
Several people, including a policeman and a young girl, died in the attack on a civilian apartment block. A baby girl was accidentally smothered by her mother as she hid in a cupboard.
Qantar was sentenced to several life sentences after the attack, and Hezbollah has consistently sought his release during prisoner negotiations since his capture.
"You ask me, will there be a deal without Samir, I say no. Absolutely not," the Reuters news agency reported Sheikh Nasrallah as saying.
Sheikh Nasrallah added that negotiations over a potential prisoner exchange were expected to start next week, but said he was still awaiting the arrival of a European UN mediator.
More than 1,100 Lebanese and about 160 Israelis died in the 34-day conflict, sparked by the capture of the two Israeli soldiers in a cross-border raid.