The 67-year-old criticised the Italian's inability to keep out David Alaba's long-range effort after just 23 seconds, as the Bianconeri suffered a 2-0 away defeat in the first leg of their Champions League quarter-final tie.
"I am sorry if I have offended Buffon by using the word 'pensioner'," Beckenbauer told Bild. "That was never my intention.
"But I still feel that Buffon should have done better with the first goal as well as the second when he failed to hold on to the ball."
The second leg of the tie will be played in Turin on Wednesday.