The most common cause of vibration is lose feet (this is probably in the manual), however can you confirm you have checked the feet and the unit is correctly secured and all feet are firmly on the ground?
Secondly it can be a loose coolant pipe or transformer which just needs clipped back \ re-secured, on this model if you can get to the back of it with a glove (as the rear radiator is hot) see if you can place your hand around the radiator and compressor and make the nose stop (you shouldnt need to apply any pressure, just resting your hand on different parts should be sufficient). If this does stop the noise, look to see if there are any bolts, scews or clips which are lose and re-secure them.
If this doesnt work, the next stage is to get an engineer out to strip the unit down or insulate \ suppress movement from the compressor.
Please let me know how you get on, if you would like an engineer to attend please let me know your postcode and I can recommend someone in you area.
The company I would recommend based on previous satisfied customers is Watts Refrigeration (01473 414196), they charge a one off fee of £59 for labour, in your case I wouldnt expect there would be any part costs, the only issue is the engineer is off next week so if you would like it fixed ASAP please give them a call today and they will see if they can fit you in before the weekend.
Failing that a colleague of mine has recommended Angelia Domestic (01473 354076) they charge a one off fee of £78 for labour.