That's why agreement and terms of agreement very important. It really depends on what has been agreed with the client, whether you have sold the rights to the images or whether you retain the rights. Copyright remains with the photographer but the right of ownership has to be spelt out or there will be disputes in cases like these. Owning a copyright does not automatically give you publishing and commercial rights.
Best to get the restaurant to settle with the client. Afterall, if there is no agreement in place, the restaurant owner can choose to prevent the client from using his premises and food for a shoot too.