"We are obviously aware of the situation and following the developments closely," said UN spokesman Stephane Dujarric.
The Palestinian detainees led by popular leader Marwan Barghouti launched the hunger strike yesterday to press for demands such as better medical services and access to telephones.
Dujarric noted that clashes have taken place in the occupied West Bank in support of the prisoners, adding: "We call on all parties to exercise maximum restraint."
Dujarric said that "as a matter of principle, wherever it may be, we always call for prisoners to be treated in a humane way."
The UN Security Council will discuss the Israeli- Palestinian conflict during an open debate on Thursday.