According to NATA 2018 brochure, (page 6, point 5)

Candidates may come from the following backgrounds: (a) 10+2 or equivalent passed/appearing; (b) 10+3 Diploma (any stream) passed/appearing recognized by Central/State Govts; (c) International Baccalaureate Diploma passed/appearing, after 10 years of Schooling.

Even on being from arts stream you can write NATA provided you have Math and English as compulsory subjects.