I first tried setting the document up using the form fields in the developer tab, but whilst I was able to paste a table into the text form field, I was unable to make any changes to it once I set the password restriction.

I also tried highlighting the text and table that I wished to remain editable and then placed a password restriction on the rest of the document - the text I highlighted remained editable, however the table and its contents did not.

I'm not sure of any other ways to be able to only restrict certain portions of a document.