The human rights organisation also said more than 150 civil society and media organisations were raided by Palestinian police in the Gaza Strip during the last week of July.
Hassan Abu Hashish, the head of Hamas' information office in Gaza, said many of the detentions were against members of "unbalanced" media outlets.
In Gaza City, Hamas' police force banned the entry of three Fatah-associated daily newspapers - al-Quds, al-Ayyam, and al-Hayat - into Gaza for three consecutive days during the end of July.
During the same period, Gaza's security forces raided the Wafa news agency offices in the Tal al-Hawa Quarter in Gaza City, according to PCHR.
They confiscated staff possessions, taking them in trucks to undisclosed locations, PCHR reported.
Emad Eid, a correspondent for the al-Manar channel, and journalist Sawwah Abu Seif, a correspondent for German TV, were taken by Gaza's security forces from their offices on July 26.
Hamas security forces asked Eid to discuss a news item published by the Ma'an news agency, of which he is director. He was released after half an hour.
Abu Hashish said that Ma'an dealt "with the violations and crimes committed by the security forces in the West Bank as a campaign to restore order", but that it dealt "with the performance of the security forces in the Gaza Strip as clear violations of law".
Hamas' security force took Abu Seif to an undisclosed location and confiscated his laptop computer.
"If the media outlets will not take responsibility for their actions, then we must rein them in ourselves," Abu Hasish said.
Thousands of government employees loyal to president Mahmoud Abbas's Fatah movement have planned to go on strike on Saturday in the Hamas-ruled Gaza Strip to support striking teachers, a trade union official said on Thursday.
About half of the teachers in the territory have not reported for work since Sunday, accusing the Hamas-run Education ministry of job discrimination over their support for Fatah.
Bassam Zakarna, the head of the pro-Fatah employees union, said thousands of other government workers would go on strike for four days starting on Saturday, unless Hamas cancelled what he called "unjust transfers" of teachers from their posts.
Hamas has denied Fatah allegations that the transfers were politically motivated and aimed at weakening the rival faction's influence.
Hamas seized the Gaza Strip from Fatah in fighting in June 2007.