My opinion

If you feel the number is not a strong point, try to emphasize the quality of citaion. Say if any of those citations refer to your work as outstanding, or anything good. Try to quote those comments in your petition letter. Just to shall that your paper has been recognized as a great source for other researchers. And you should also try to obtain letters from those who cited your paper, and hopefully make them say in their letter that your paper and study is of great value.