One idea:
1. Drill vertical holes into the bottom of the block.
2. Weld onto the beam threaded studs - of appropriate length - perhaps 2/3 of the way through the block.
3. Epoxy them in place on the beam.

Another:
1. Weld vertical steel plates on the top of the beam to align with block head joints
2. Perhaps space plates every third head joint.
3. Set blocks between the plates.

Another:
1. There should be some strap ties used for brick that can be screwed or shot down to the beam flange and extended up into the head joints.

Finally:
1. Drill holes through the first course of blocks.
2. Provide through bolts through holes in the top flange and bolted down to the bottom course using washer plates.
3. Second course must be cut to allow space for the bolt heads (this is a negative on this idea)

Another option echoing what is often done for the lateral support of the tops of block walls. If this occupies to much space, you might do something similar by, essentially, fabbing an upturned channel onto the top of the beam into which the masonry would be set.