Ronaldo ended his nine-year association with Real Madrid when he agreed a switch to the Serie A champions worth $112million.
The Portuguese forward released a statement via Madrid's website to explain his reason for requesting to leave once the deal was announced, citing the need for a "new cycle" at this stage in his career.
However, Tebas believes the move was also partially motivated by money, with the player able to earn more in Italy.
"He'll earn more money than here," Tebas said.
"I think that fiscally it favours him to go to Italy. Here, in Spain, we have a problem with fiscal competition.
"Out of the biggest leagues, Spain is where the players have the worst tax situation.
"It's not that elsewhere the rate is so much lower, but when you're earning significant sums then these little differences in rates translate to a lot of money for the players."
A five-time Ballon d'Or winner and Madrid's all-time leading scorer, Ronaldo signed a four-year contract with Juve.