The change was among ideas floated by the Number 10 policy unit after being asked to come up with new ways to extend personal freedoms, the Daily Mail reported.
Among other recommendations was a relaxation of laws against nudity but a Downing Street spokesman denied claims that was being considered.
"The Prime Minister considers the idea of lowering the age of consent to be offensive," he said - insisting there were no plans to do so.
Asked about reforms to nudity laws, he added: "It's not something that the Prime Minister is considering."
Monday's mid-term review of the Tory/Lib Dem coalition said the Government would take further steps to "limit the scope" of the state "and extend our freedoms".
The age of consent has been 16 since 1875 but there have been calls for it to be lowered because so many teenagers are sexually active at a younger age.
Criminalising young people makes it harder to advise them on issues such as birth control and pregnancy and safeguards could be included to ensure it only applied to youngsters of a similar age, campaigners suggest.