Place a cloth over the spot. An iron set to medium and iron over the cloth. May take a few passes.
Depending on the type of wood, I've used a cut walnut and rubbed it vigorously back and forth over the mark.
To remove white rings left by wet glasses on wood furniture, mix equal parts vinegar and olive oil and apply it with a soft cloth while moving with the wood grain. Use another clean, soft cloth to shine it up. To get white water rings off leather furniture, dab them with a sponge soaked in full-strength white vinegar.
Vaseline absorbs the water
This may help you: https://www.hometalk.com/41678838/how-to-remove-water-stains-from-wood-furniture