Yes. Besides lowering ISO, a few things can reduce visible noise:

• keep the sensor cool: higher temperatures increase thermal noise, so a hot camera will often produce noisier images.
• expose a bit brighter when possible: slight overexposure can improve the signal-to-noise ratio, especially if you shoot RAW and then bring the exposure back down in post. This is often called “expose to the right,” but avoid clipping highlights.
• average multiple frames: if the subject and camera are stable, taking several shots and averaging/stacking them can reduce random noise.
• reduce output resolution: downsizing the image makes noise less visible.

In general, noise is strongly affected by how much actual light reaches the sensor. If you can’t lower ISO, getting a stronger exposure and preserving highlights is usually the most practical way to improve results.