In a joint statement from both the ECB and Pietersen himself, the 32-year-old has confessed to sending texts to members of the South African squad which criticised some of his England teammates.
"I did send what you might call provocative texts to my close friends in the SA team. The texts were meant as banter between close friends," said Pietersen. "I need to rein myself in sometimes. I apologise to Straussy and the team for the inappropriate remarks at the press conference and for the texts.
"I truly didn't mean to cause upset or tension particularly with important games at stake."
Meanwhile, the statement from England managing director Hugh Morris read: "We are in receipt of Kevin's apology, but further discussions need to take place to establish whether it is possible to regain the trust and mutual respect required to ensure all parties are able to focus on playing cricket and to maintain the unity of purpose that has served us so well in recent years.
"Critically, those discussions should take place behind closed doors, rather than in the media spotlight. A successful conclusion to this process is in everyone's best interests and is required for Kevin Pietersen's potential selection in all forms of the game to be considered.
"At the moment we have an important Investec Test match to focus on and therefore ECB will make no further comment until such time as is appropriate."
Pietersen has been dropped from the squad for the final Test against South Africa later this week.