How to get money back from seller of land if area of land is smaller than agreement

Why had you measured the purchased land at the time of registration of sale-deed?

Now you have no other option but to file a civil suit against that person and get the refund of excess amount.

It is your duty to purchase the land after getting such a measurement.  It all depends on facts of the case if your seller has himself purchased the land and like you ignored measuring the land, and taken the measurement shown in the title deed as standard, then you can not prove such ulterior motives.  If there is no malafide intention and if the difference is not more, just issue a legal notice and after receiving such a response, be guided by your advocate.   Some of these litigations are not worth fighting, as you have to incur more expenditure and time on such vexatious exercises without a certainty in the outcome.

It is your duty to purchase the land after getting such a measurement.  It all depends on facts of the case if your seller has himself purchased the land and like you ignored measuring the land, and taken the measurement shown in the title deed as standard, then you can not prove such ulterior motives.  If there is no malafide intention and if the difference is not more, just issue a legal notice and after receiving such a response, be guided by your advocate.   Some of these litigations are not worth fighting, as you have to incur more expenditure and time on such vexatious exercises without certainty in the outcome.