As others have said, lasers do exist which don't rely on electricity. The soviets apparently experimented with a laser pistol during their space program, to blind other astronauts or satellite cameras. There's a bit of a description of it here, along with some photos of the (very home-made looking) prototype.
The Soviet Laser Pistol. In brief, this gun is a charge-pumped design using an yttrium aluminum garnet (other sources say ruby) gain medium, and a zirconium flash bulb, which burned the zirconium in an oxygen atmosphere to generate an intense, single use flash (similar to old single use camera flashes). While igniting the zirconium was done electrically in that pistol, presumably you could do this with other means: a flint-lock rifle with the flash tray filled with zirconium, and the barrel filled with ruby etc. would probably work in a sci-fi setting.
As a slight aside, you said:
Electricity has not been discovered.
This doesn't necessarily mean that it can't be an electrically-based design: historically electricity was very poorly understood in the early days. Ancient Greeks knew that amber could be rubbed with a cloth and attract small particles (this is a common high-school experiment) which lead to a lot of early 'friction machine' static generators which rotated a glass sphere against a woolen cloth. These were invented before electricity was understood, and were assumed to work on some form of magnetism Electrostatic generator.
Similarly, look up the Piezo-electric effect. When certain crystals are squeezed, they produce a voltage (cigarette lighters and gas stove/barbeque igniters use this principal, with a spring-loaded hammer striking a tiny crystal to produce a spark). It's possible your civilisation could have discovered this effect without actually understanding or discovering electricity. A water-wheel hooked up to a bunch of trip-hammers pounding on crystals, for example.