Santa Cruz is set to complete his move to the Spanish side later on Friday, once he has completed a medical.
He told a Paraguay radio station: "I had in mind to return to Betis, that was always my idea because Betis has always treated me very well.
"But in the last weeks there was interest from Malaga. I would have the chance to play the Champions League there and that was the reason I accepted to be transferred to that team.
"I am sure that my family is going to feel very well at Malaga.
"This is the last year of my contract at Manchester, and in December I would be able to negotiate with other teams.
"But now there is a deal between both clubs, so I have travelled to Malaga for the medical tests, and then I will sign my contract."