In the first raid, the helicopter fired two missiles at a workshop, then returned after several minutes, firing another eight rockets at targets in the same area, one of which did not explode.
Palestinian medical sources said four people were slightly injured in the raids, two of whom were suffering from shock.
The two workshops were completely destroyed in the raids, and several nearby houses sustained minor damage.
Local witnesses said one of the workshops belonged to Musa Abu Sabaan, and the second to the al-Fasih family.
The Israeli army confirmed the strikes, saying the raids had
targeted the al-Fasih workshop and the Abu Sabaan workshop.
"Two workshops which were part of the weapons-production
industry in the Gaza Strip were destroyed," an army spokesman alleged.
"They were being used by the Hamas terrorist organisation and other terrorist organisations to produce a variety of weapons,
notably Qassam rockets," he claimed.
Earlier on Friday, a makeshift Palestinian rocket fired from the
Gaza Strip hit a residential area in the southern Israeli town of Sderot.
No one was injured in the strike, but it caused damage to one
house and a woman living there had to be treated for shock.