A system and method for coordinating the transmission and receipt of large data blocks as a series of smaller burst transfers through an intermediate interconnect coupling a pair of devices. A device receiving a transaction request ("initiator") specifies the data block size of the requested transaction to the other device ("target"). The target response will indicate that it is committed to the transaction, that it does not support requested transactions of the specified data block size, or that it currently lacks the buffer capacity to commit to the requested transaction. In the first instance, the initiator and target exchange the data block through the interconnect as a series of burst transfers until all data has been transferred, at which time the initiator (for read transactions) or the target (for write transactions) forwards the transferred data as a data block of the specified size. When the response indicates the target supports only smaller data block sizes, the initiator may adjust the specified data block size accordingly and proceed with the transaction once the target is committed. When the target response indicates insufficient buffers are currently available to accommodate data of a supported block size, the transaction may proceed as a series of independent burst transfers until all data is transferred or buffers sufficient for the specified block size become available.