Shock reports in the Portuguese and Spanish press earlier this week suggested that the 32-year-old wants out of the Bernabeu this summer.
The four-time Ballon d'Or winner is accused of breaching his tax obligations, totalling around £13m, and has grown upset by the lack of support given to him by Madrid chiefs.
Santos insists that all focus is currently on the Confederations Cup, however, which Portugal get under way on Sunday afternoon against Mexico, backing Ronaldo to put the ongoing concerns behind him.
"I've known him for many years," he told reporters in Kazin. "I was his last coach in Portugal when he was 18 years old. I can put my hands on the fire for his character and integrity, as a man and an athlete. That's my clear statement. I trust him 100% as an athlete and as a man.
"We are here to represent Portugal in the Confederations Cup. I have a pact from the beginning with my players, all personal issues not connected to the team are left out. We are prepared for a game with a good opponent, we have seen many videos of them, they have a lot of technical ability, they are very strong but we are prepared to win."
Paris Saint-Germain, AC Milan and Manchester United are all understood to be in the running to sign Ronaldo, who has netted an unrivalled 406 goals for Madrid in 394 appearances.