A man was left needing medical treatment after an incident in Rubery Rednal.
Officers are eager to identify the man pictured as they believe he may have information which could be helpful to their investigation.
They also ask anyone who was in the area at the time or who witnessed the incident to come forward.
Any information call 101 quoting incident number 355S of 30 April. Alternatively, contact Crimestoppers anonymously on 0800 555 111 or visit www.crimestoppers-uk.org