All I've found is Cruz commenting that racists groups are making rob calls on Trumps behalf warning people not to vote for a Cuban.
So you'll have to substantiate your claim.
http://finance.yahoo.com/news/really-sad-ted-cruz-rips-173343510.html;_ylt=AwrBT8X48txWyEYAONZXNyoA;_ylu=X3oDMTEyMWdjb2Q0BGNvbG8DYmYxBHBvcwM5BHZ0aWQDQjE3MjRfMQRzZWMDc3I-
http://latino.foxnews.com/latino/politics/2016/02/29/rivals-slam-trump-for-refusal-to-denounce-endorsement-from-former-kkk-leader/
http://www.businessinsider.com/ted-cruz-donald-trump-kkk-david-duke-2016-2