The group, members of a political wing of the mainstream Fatah movement, occupied an Interior Ministry office in the Dair al-Balah refugee camp, forced everyone to leave and stood guard outside.
A spokesmen for the men said they wanted jobs.
"Our efforts so far have been fruitless, therefore we have been forced to take action," he told Reuters. "Today we are closing the Interior Ministry and post office to make sure our message gets through."
The group later ended its protest at the office after telephone calls between the group and the Palestinian Authority, reported Sammir Abu Shammalah, Aljazeera's correspondent in Palestine. The two sides agreed to meet on Monday to address issues of living conditions and jobs.
Before the protest ended, dozens of Fatah members entered Palestinian Authority offices in Dair al-Balah and ordered the employees to leave the buildings, Abu Shammalah said.
Separately, about 30 gunmen and relatives of a policeman killed in a gunbattle with a Palestinian clan feud on Thursday stood at a border crossing with Egypt and threatened to bar Palestinian officials from reaching the Rafah terminal, witnesses and security sources said.
Police at the terminal said it was operating normally with European monitors on hand, despite the protest, which was joined by members of the al-Aqsa Martyrs' Brigades.
Palestinian travellers wait at the
Rafah border crossing on Friday
Colleagues of the slain officer blocked the same terminal on Friday, effectively shutting the border crossing for several hours.
In the West Bank on Saturday, Israeli occupation forces stormed the headquarters of Palestinian military intelligence in the city of Jenin, Aljazeera's correspondent in Palestine reported.
The Israeli army is holding two employees at the headquarters, the correspondent said, and has imposed a curfew on the Jenin refugee camp for a second consecutive day.