The political faction of Hamas is running for the first time, challenging Palestinian Authority Chairman Mahmoud Abbas' Fatah Party. Polls indicate Hamas could win about 30 percent of the 132 seats.
Zahar said he would be open to negotiations with Israel, but only if the Israelis have something to offer, CNN reported.
"We are not going to meet them just for meeting," Zahar said after he voted in Gaza, adding many previous meetings have "ended with nothing."
However, he said he would never recognize Israel as a state.
Polls opened Wednesday in Gaza, the West Bank and East Jerusalem for about 1.3 million Palestinians.