i am pursuing bcom and i want to go us for pg.i have heard that american university does not accept 3 yrs degree of graduation.is this true?

Yes, it is very much true that one required a 4 year degree or equivalent to be eligible for master courses in USA. Incase your degree is a 3 year degree, you should pursue a PG diploma of 1 year duration and then apply to US. Hope my answer has solved your query. If it has, kindly mark it as best a