A Palestinian security source said security men confiscated the weapons following a heated argument with the fighters late on Tuesday.
"Members of the security forces in northern Gaza stopped a militant group from firing three mortar shells into Israel," he said.
Newly-installed Palestinian leader Mahmud Abbas ordered the deployment of about 2500 Palestinian police and security forces in northern Gaza five days ago to stop Palestinian resistance fighters from launching rocket attacks at Israeli targets.
But for a few stray incidents, the deployment has been accompanied by a marked lull in violence in Gaza.
Palestinian medics recovered the body of a Gaza man shot dead by Israeli troops after he reportedly entered a closed military zone on Monday.
On Tuesday, Israeli soldiers shot and lightly wounded three Palestinians in a car that apparently went through a red light at a major highway junction checkpoint in south Gaza.
Palestinian and Israeli officials meanwhile have agreed to extend the deployment of Palestinian security forces to several flashpoint areas in central and southern Gaza with the aim of preventing attacks being launched from there.
"Members of the security forces in northern Gaza stopped a militant group from firing three mortar shells into Israel"
Palestinian security source
"There is Israeli-Palestinian agreement to deploy Palestinian forces in the southern area, and in central Gaza," a Palestinian official said.
Under the deal, Palestinian troops could start to deploy in central and southern Gaza as early as Wednesday.
The Israeli army had no comment. An Israeli source said the deal still required approval from higher officials, but Israel wants to encourage Abbas' efforts to halt violence.