Photo of Abdul Rashid Ghazi courtesy of the BBC
Abdul Rashid Ghazi's defiant statement came as the stand-off, which has seen 19 people killed, entered a fourth day.
President Pervez Musharraf has ordered his security forces to hold back from a full assault.
Gen Musharraf is said to be anxious to avoid casualties among women and girls still inside the complex.
Mr Ghazi had earlier said he would leave the mosque on certain conditions, including being allowed to look after his ailing mother.
The offer to end the confrontation came after Mr Ghazi's brother Maulana Abdul Aziz - leader of the mosque - was captured while trying to escape wearing a woman's burqa.
Pakistani government ministers dismissed the deal.
Shortly afterwards, Mr Ghazi said he would not surrender unconditionally.
"We have decided that we can be martyred but we will not surrender. We are ready for our heads to be cut off but we will not bow to them," he said. Pakistan cleric makes defiant vow (more)
Mark Alexander
