No, there is not. It's an open issue. https://github.com/asciidoctor/asciidoctor/issues/1338 And since it is a language change, it will require ratification by the AsciiDoc language spec project, which is still getting underway. It's not likely to be resolved this year. However, it is something we plan to write into the first version of the specification, if possible.
What you can do is set a role on the table, then use CSS to target specific cells. You could even have a lot of different roles that target cells in different ways. So it is possible to do...it just happens to be more clumsy.