You don't say how old you are, which country you're in/from or what religion you follow.
In the UK there are Asian helplines, for instance, who deal with these sort of problems.
I'm not in your situation, but I'd say this to you - tell your parents that you respect their choice, but you'd like a while longer to make a decision. Then, as has been said, get to know this man further. Are you chaperoned when out together? Even though you've known him as a friend for a long time, can you ask him if he really feels for you, or whether he, too, is being pushed? Ask him what he'd expect from you if you were to marry. Would you be allowed to follow a chosen career path, for instance, or expected to start a family immediately? If you can look at both sides from a detached point of view, you might actually find that this man has the qualities needed for a good marriage. I wish you the best of luck.