A.plot() is inherently a 3D object. Its save method can save to various 2D image formats (but not .pgf), HTML or various specialized 3D formats. Its save_image method does not include .pgf as a valid output format.
Your best bet seems to start from one of these formats (or HTML) and convert it via the targe tool(s) for the choosen format. It might be possible to het three.js to output a Tikz picture...
It might also be possible to add Tikz output to the relevant save_image (or possibly save) method. Care to file a ticket for this ?