If a company manufactures new computers, which is the correct way to describe this process; 'do computers' or 'make computers'? I think it is 'make computers', because 'do' refers to a physical action while make refers to a new creation of something, but I'm not sure which is correct.
I guess that you are asking this question because عـَمـَل means both make and do.
Here is the definition of make from the Cambridge Dictionary: "to produce something, often using a particular substance or material". You are right: in writing or in formal conversation, make is the best verb to describe what a manufacturer does.
This company makes computers
Note that do has another meaning, apart from carrying out an action. According to the Cambridge Dictionary, it can also mean "to make, produce, or create something". I would regard this usage as quite informal. Here is an example:
This café does the best carrot cake in town.
So, in informal conversation, you could say
This company does computers