All international students and scholars are required to report to the U.S. tax service (known as the Internal Revenue Service) each year — even if they did not work during the prior year. You will not necessarily need to pay taxes; but you must at least report your presence in the U.S. This is a legal requirement.
Although OGA and OGS staff unfortunately cannot advise on tax issues, OGS has provided some basic information here:
http://www.nyu.edu/global/international-immigration-services/students/inbound-to-nyc/active/taxes.html