Among those detained were four Hamas lawmakers, a university professor and a former Hamas deputy prime minister.
The Israeli military said in a statement that those arrested were involved in "restoring the Hamas administrative branch." Hamas in the West Bank has been the target of a crackdown by Israel and the security forces of moderate Palestinian President Mahmoud Abbas in the past two years, ever since the militants seized Gaza by force.
The detentions appear to be an attempt to pressure the group after the failure of recent efforts to win the release of an Israeli soldier, Sgt. Gilad Schalit, who is being held by Hamas in Gaza.
Ahmed Bahar, a Hamas leader in Gaza, denounced the arrests as "immoral blackmail by the Zionist occupation."
Israel has detained dozens of Hamas politicians in the West Bank on various occasions following the capture of Schalit, 22, in a cross-border raid in June 2006.
The detainees in the latest raid include Nasser Shaer, a former Palestinian deputy prime minister, and four Hamas lawmakers. Some have already been detained in the past and released.
Outgoing Israeli Prime Minister Ehud Olmert had hoped to secure the release of Schalit before a new Israeli government is formed, possibly within days. To that end, he dispatched two senior envoys to Cairo over the weekend to try to clinch an Egyptian-brokered deal with Hamas, which rules Gaza and has no direct ties with Israel.
But the envoys returned to Israel without a deal in hand, and on Tuesday Olmert declared that Israel would not free all of the hundreds of Palestinian prisoners the Islamic militants demanded in exchange.
Some were involved in attacks that killed dozens of Israelis, and Olmert insisted that there were "red lines" that Israel "will not cross."
Incoming Prime Minister Benjamin Netanyahu, who is expected to partner with hawkish parties in Israel's new government, has not commented on the failed release efforts or how he plans to deal with Schalit's case.
The failure of the prisoner swap talks threatens to set off a long chain reaction of setbacks. Israel has vowed not to lift its crushing blockade of impoverished Gaza until Schalit is returned home. That could seriously impede reconstruction there after Israel's recent military offensive because building materials and equipment won't be able to enter the territory, home to 1.4 million Palestinians.
The continued blockade could also hamper efforts to cement a long-term truce between Israel and Hamas, which in turn would carry the threat of a sudden escalation in the low-level violence that has continued since the war ended on Jan. 18.
On Wednesday, Schalit's father, Noam, blamed Olmert for failing to free his son and said the family would dismantle a protest tent it set up outside Olmert's residence on Saturday - 1,000 days since the serviceman was captured.