The attack took place outside John Rigby School, Polhill Avenue, Bedford, between 3.15pm and 3.30pm, last Thursday (January 14).
Police are hoping witnesses will come forward with information.
The offender is described as white, of average build and in his late 20s.
Investigating officer PC Richard Marshall said: “Racial attacks of any kind are unacceptable and will not be tolerated.
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“This incident has understandably left the victim shaken and we ask anyone who has any information that could assist our enquiries to come forward.”
Anyone with information is asked to contact PC Marshall on 101 or call Crimestoppers anonymously on 0800 555 111.