The International Cricket Council has banned Upul Tharanga for three months after the Sri Lanka opener failed a drugs test.
The 26-year-old pleaded guilty after taking a herbal remedy during the World Cup to ease a shoulder injury.
"Tharanga had no intention to enhance his sporting performance or to mask the use of a performance enhancing substance," said an ICC statement.
Tharanga is not part of the Sri Lanka one-day squad currently in England.
The left-hander, who has the right of appeal, gave the positive sample in the aftermath of Sri Lanka's semi-final win over New Zealand.
"I apologise to the fans and followers of Sri Lanka cricket for inadvertently committing an offence," said Tharanga, a limited-overs specialist who has played in 121 one-day internationals since his debut in 2005 but only 15 Tests.
"I hope my fellow sportsmen will learn from my experience and be more vigilant when taking medical treatment, so that their careers do not suffer in the way that mine has."
His ban, which extends to all forms of the game, has been backdated to 9 May, so he would be available from 9 August, the day before Sri Lanka begin a five-match one-day series against Australia.
"We recognise that Upul has not been found guilty of deliberately cheating, but the ICC maintains its zero-tolerance approach towards doping for the benefit of all its stakeholders," said ICC chief executive Haroon Lorgat.
"Cases like this serve as a reminder to all players that they must take great care and personal responsibility at all times for the substances that they consume.
"I am satisfied with the tribunal's decision and pleased at the way the ICC has handled this case with both sensitivity and efficiency."