He published a statement on his official website and Facebook page that reads in part:
Taking all of this into account, I feel that this is a time for me and the band to show solidarity for those freedom fighters. As a result, and with deepest apologies to our dedicated fans in Greensboro, we have canceled our show scheduled for Sunday, April 10th. Some things are more important than a rock show and this fight against prejudice and bigotry — which is happening as I write — is one of them. It is the strongest means I have for raising my voice in opposition to those who continue to push us backwards instead of forwards.
The complete statement can be read on brucespringsteen.net