The concessions made by the prison governor affect only the Ashkelon detainees.
The other 3200 Palestinian prisoners who have been protesting for better conditions remain on hunger strike, the Bethlehem-based Palestinian prisoners' association said on Friday.
The association said the prison authorities had agreed to end practices of placing in small cells those prisoners who were being disciplined, as well as of "humiliating" body searches of prisoners who had been stripped naked.
The prison would also provide better food and relax restrictions on visits by prisoners' relatives.
The suspension of the strike until Monday was to allow prisoners to pursue talks with the authorities on other demands, as well as to see whether the improved measures would be extended to other facilities, the group said.
About 8000 Palestinians are currently held in Israeli prisons, with up to a half thought to have been refusing food.
More than 13 international organisations operating in the Palestinian territories have expressed concern over the strike.
The Israeli government had said it would not negotiate with the prisoners, and Public Security Minister Tzahi Hanegbi had said he was prepared to watch them die.
But in a statement issued on Friday, the UN's top envoy to the region urged Israel to resolve its dispute with the prisoners and guarantee their health.
Terje Roed-Larsen "called on the Israeli authorities to comply with its international obligations and to make every effort to find, with the prisoners, an appropriate resolution to the hunger strike.
"The UN agencies and offices remind Israel of its obligations under the fourth Geneva Convention and relevant international human rights instruments which provide for the protection of detainees and prisoners," he added.