Reading bytes from IPFS file using API

I am trying to read bytes from BlockGet() function in go-ipfs-api from a hash file with large amount of data. I have a buffer of fixed size which is used to store data from the hash file, due to its fixed size I am unable to store the large amount of data.
Is there any way to read bytes of the file partially (given size i.e. buffer size) in the buffer and later on continue to read bytes from last cursor position?