Palestinian gunmen have exchanged fire with police at an election office in Gaza City, ahead of the January parliamentary poll.
Gunmen loyal to Fatah stormed offices in several cities this month
Militants linked to the ruling Fatah party have also forced the closure of offices in two Gaza towns, in a protest against Fatah's candidate list.
The Palestinian leader is due to try to end a damaging split in the party by entering a unified list of contenders.
He has also appealed to militant groups to halt rocket attacks on Israel.
However, Hamas and Islamic Jihad said they would not extend their ceasefire with Israel beyond the end of this year.
"Renewing the truce will give it an opportunity to attack the resistance," an Islamic Jihad leader said.
There were more Israeli air strikes against targets in Gaza early on Wednesday morning, but there are no reports of casualties.
The Israeli army said the aircraft had attacked access roads used by militants to fire rockets at Israeli targets.
Armed groups have been able to fire missiles deeper into Israel since it withdrew from Gaza in September.
Militants traded fire with police outside the Central Elections Committee (CEC) site in Gaza City, before leaving. No injuries were immediately reported.
Scheduled for 25 January; originally set for July 2005
132 members elected to Palestinian Legislative Council (PLC)
Fatah and Hamas are main contenders
First time Hamas participates in parliamentary poll
Israel says Hamas cannot take part under a 1995 agreement
Last parliamentary elections held in 1996
Elsewhere in Gaza, gunmen from al-Aqsa Martyrs Brigade stormed poll offices in Khan Younis and surrounded one in Rafah, prompting both to close.
Militants said they had taken action because they wanted to be represented on Fatah's list of candidates, according to the AFP news agency.
"Our voices have been lost," the leader of the group in Khan Younis said.
Fatah has been in disarray since a group of younger members led by jailed West Bank intifada leader Marwan Barghouti broke away.
The rival faction submitted its own list of candidates for the poll two weeks ago.
Correspondents say the so-called old and new guard have disagreed for some time over the direction the party should take.
There are fears that the infighting could throw Palestinian politics into chaos and could even threaten the election process, they say.
Gunmen linked to the party have staged daily temporary takeovers of Palestinian Authority buildings, to demand jobs and an end to corruption.
The 25 January poll will be only the second since the establishment of the Palestinian Authority in 1995.
Fatah is expected to face a strong challenge from Hamas.