Abdallah Barghouti, who is serving 67 life terms, was caught speaking to a radio station aired in the besieged Gaza Strip, Sivan Weizman said.
Barghouti used a mobile telephone that he had "smuggled into the prison where he is being held, and has been placed in an isolation cell," she added.
"We are steadfast and waiting patiently, according to your promise to us,” Barghouti said in his interview with the radio station, adding, "We will continue adhering to it whether we are released today or in another thousand years.”
Israel has not made clear how long Barghouti would be held in solitary confinement.
The Palestinian resistance fighter, affiliated with the Ezzedine al-Qassam Brigades, was arrested in 2003 and sentenced to 67 life terms for his alleged involvement in several attacks against Israelis, including the bombing of a restaurant in al-Quds in 2001 that killed 15 Zionists and wounded dozens more.
Abdullah Barghouti is a relative of Marwan Barghouti, the former head of the Palestinian Fatah party that operates in the occupied West Bank.
Abdullah Barghouti was the leader of the second Palestinian intifada (uprising) which lasted from 2000 to 2005.
Zionist troops frequently raid the houses of Palestinians in the West Bank and Gaza, arresting many people, who are then transferred to Israeli prisons, where they are kept without any charges brought against them.
According to the Palestinian Prisoners’ Affairs Committee (PPAC), there are more than 7,000 Palestinian prisoners who are currently held in some 17 Zionist jails, dozens of whom are serving multiple life sentences.