With the corporation's Royal Charter due for renewal in 2016, the Prime Minister said he remained a supporter of the TV licence as the means of financing the BBC.
However he made clear that it needed to maximise its own output and avoid becoming over-reliant on imports like Borgen, The Bridge and The Killing.
"I'm in favour of the licence fee, but I'm in favour of making sure they get good value for money," he said during a question-and-answer session in Birmingham on Heart, Capital and Smooth Radio.
"I often wonder why is it we make something amazing like The Office and we just make eight episodes. You've got Modern Family and they're churning out series seven or something.
"So, let's try and make sure we produce the hits of the future, rather than having to brush up on our Danish and read the subtitles."
A BBC spokesman said: "With global hits like Doctor Who, Sherlock and Call The Midwife, the vast majority of programming on the BBC is home-grown. Imports make up a very, very small percentage of our output."