Do not alter its support or position without model-specific guidance. Movement can affect connections, stability and access.
What the observation means
Noise may originate from pipework, fittings or a fault rather than direct contact with the floor. A soft pad can hide a symptom while allowing unwanted movement.
A useful next step
Describe when vibration occurs and any recent changes. Keep the unit in its approved arrangement and seek assessment if the noise has changed. Do not lift connected equipment, loosen pipe clips or pack it with household materials to silence it.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.