If you are really worried whether they will accept you or not, just contact their graduate admissions office or your program's contact and simply ask them.
There are some organisations such as WES which could translate your degree into the American system and they will certify that your 3 year Bachelor's is equal to their 4 years and will also translate your degree class into their GPA system. However do not attempt this unless your university asks for this for 1) this will cost you some money 2) some universites like to translate the degree credentials on their own.