Terry was axed as captain 13 months ago amid allegations over his private life and has now been controversially reinstated by the Italian.
"Sometimes I regret what happened. It is possible to do some things better, but it is the past," said Capello.
"I can understand everything, but I need to make decisions."
Manchester United defender Ferdinand's current absence from the squad because of a calf injury, plus the unavailability of vice-captain Steven Gerrard with a groin problem, meant Capello had a captaincy decision to make, and he defended his choice.
"Something happened in my mind when I saw the armband being passed around during our game in Copenhagen [against Denmark on 9 February]," said the Italian.
"We changed it in the second half and it was unfair for John Terry to see this.
"I thought that it was time for John Terry, after punishment, to return and be captain.
"I spoke with the players and personally with some players, and I spoke with the squad before I decided that John Terry will be the captain, and all the players were happy because John Terry was always a very important leader on the pitch and to the team."
Capello said that he had tried to meet former captain Ferdinand but was unable to do so.
"I tried to meet him [Ferdinand] when Manchester United played against Marseille but he told me no," said Capello.
"It didn't happen, he didn't come. I was in the directors' box. You will have to ask him."