Cameron's office said the two discussed the case during a meeting at the Munich security conference.
Abdel Baset al-Megrahi is the only person convicted of the 1988 bombing of a Pan Am airliner over Scotland, which killed all 259 people aboard - mainly Americans - and 11 on the ground.
He was released by Scotland's government on compassionate grounds after being diagnosed with cancer, and is currently receiving treatment in his native Libya.
A cable disclosed by WikiLeaks showed Britain's former government offered advice to Libya on securing al-Megrahi's release.
Cameron told Clinton a new report on the actions of the Scottish government - which authorized al-Megrahi's release - and British government could be completed as early as next week, according to a senior U.S. official.
The official spoke on condition of anonymity to discuss a private diplomatic conversation.
Matthew Lee contributed to this report.