The arrests came just days after a Palestinian unity government was inaugurated in Ramallah, based on an agreement between Hamas and the PLO.
In Nablus, PA forces detained 16-year-old Naji Tabouq, 17-year-old Mahmoud al-Anati, Muhammad Tahsin al-Nimir, Zahi al-Dawwaya, Mahmoud Tabouq, Muhammad Antar, Said Abu Lawi, Yasan al-Bahsh, Ali al-Bahsh, Tamir Abhu Shamat, Muhammad Heiron, and Abboud Heiron.
In the Ramallah district, PA forces arrested Sami Thabit from the village of Shuqba and two men from the Umm al-Sharayit neighborhood of Ramallah.
Meanwhile, in Hebron, PA forces detained Jaafar Naim Misk, the Hamas statement said.
The PA also sent summons for interrogation to seven other Hamas supporters in Ramallah, Bethlehem, Tubas, and Qalqiliya, the statement added.
As the unity government prepares to enter its second week, political detentions threaten to drive a wedge between Hamas and the Fatah-led PLO.
Another point of tension has been the fate of employees formerly employed by the Hamas-run government in the Gaza Strip.
Hamas and the PLO, it seems, neglected to reach an agreement on whether the newly-formed unity government would take over paying the 50,000 employees, including security officers.
The financial dispute began Wednesday when security officers of the Hamas government prevented PA employees from withdrawing their salaries, saying they should not receive their salaries until employees of the former government did as well.