The Hamas interior ministry, however, denied any arrests had been made for “resistance against the occupation.”
Hamas’s “internal security apparatus in the last two days arrested two mujahedeen. One was released after several hours. The other is still detained,” a Salafist source told AFP on condition of anonymity.
The source said it was part of a “campaign to pursue Salafists after the targeting of Israel with rockets.”
A Gaza-based Salafist group claimed firing rockets on Tuesday and Wednesday that landed in open fields, causing no damage or casualties. In response, Israel carried out two air strikes, also without causing harm.
Crossfire between Gaza and Israel began on Tuesday after the death of Maysara Abu Hamdiyeh, a Palestinian prisoner who died from cancer after allegedly being denied medical treatment in Israeli jails.
Protests and clashes have erupted in the West Bank as a response, and many cities observed a general strike Wednesday.
Two Palestinian teenagers were shot dead late Wednesday in one of the clashes by an Israeli army military post in Tulkarem.
The Islamist movement Hamas, which has ruled the Gaza Strip since 2007, has regularly cracked down on hardline Salafists in the territory, notably in 2009.
“Our security apparatus is part of the resistance and does not arrest anyone who resists the occupation. On the contrary, we encourage resistance,” Islam Shahwan, interior ministry spokesman, said.
The Mujahedeen Shura Council, meanwhile, urged “the rational-minded in Hamas to pressure its security to release Salafists” in a statement on Thursday.
In response to the rocket attacks Israel has tightened a maritime restriction barring Gaza fishermen from operating more than three nautical miles off the Mediterranean coast.
The already stringent limits were tightened from six miles on March 21 after Salafist militants fired two rockets at southern Israel as US President Barack Obama was visiting the country.
Israel also closed down Kerem Shalom, Gaza’s only goods crossing, and imposed tight restrictions on travel into and out of the territory via the northern Erez terminal which was limited to medical emergencies only.
A week later, the restrictions on the two crossings were lifted and Kerem Shalom and Erez began operating as normal.
But the fishing limitations were left in place, Palestinian officials said, with the Israeli army confirming it was a political decision taken after an uptick in rocket fire this week.
Last week, two Israeli rights groups Gisha and B’Tselem, demanded that Israel lift the fishing restrictions, saying the measure amounted to “collective punishment.”