The 26-year-old Pietersen sustained the injury while fielding for his county in Monday's Provident Trophy match against Ireland, in which he scored a match-winning 66.
He was taken for a precautionary MRI scan and the results persuaded the England and Wales Cricket Board's medical team that he should not be risked in the County Championship match against Lancashire on Wednesday.
A further assessment of the injury will be made later in the week but it is not yet known if it could threaten his participation in the Test opener on May 17.
"It is extremely annoying. The muscle is torn and I'll have to see how it responds to treatment before I know if I'll be able to play in the Test,'' Pietersen told the Daily Mail.
"What I do know is that I'm desperate not to miss it and will do everything I can to get fit."