Running tsc with --declaration option generates the .d.ts file with all the declaration, private included.
Is there a way to produce a .d.ts file with only exported types and, for classes, only public methods and attributes?
It's not possible.
Typescript keeps privates in generated .d.ts files to support further inheritance.
Because there is no such thing as 'private' in JS, declaring a type that derives from a d.ts type with stripped out privates could cause problems if you accidentally will have a name collision in your child class. That will be very difficult to find and fix.