I just want to know the upper and lower limits of levels in asphalt pavement as per the international standards. I have a problem, where, the tolerance is set as +/-4mm, which is highjly impossible to attain.

There is a great variation of tolerances for HMA pavements. I do not know of the international standard. Many states in the US use a rideability specification which sets forth a requirement of a maximum number of inches deviation in a mile of pavement.
If I have computed correctly, 4 mm is about 5/32 inches or just over 1/8 inch.
You don't say what length in which the +/-4mm is allowed.
The enclosed spec (section 406.13) requires 1/8 inch (less than 4mm) in 10 feet.
But that is just an example I was able to find. It may not be the same type of construction you are involved in and you may have a different mix that is impossible to place at that tolerance.
But at least one state considers it to be reasonable for their specification.
The Federal Highway Administration (FHWA) may have some suggestions for you.
http://radio-weblogs.com/0132378/stories/2003/12/02/njdotSpecificationsSection406SuperpaveHma.html