Ziggy Liaquat, managing director of exam board Edexcel, insisted there was a "very strong set of results" and said that students "should be very proud".
He added that the fall in A-grades was "marginal" and said: "The standard needed to reach an A-grade has not changed."
Mr Liaquat highlighted the increase in the number of students taking STEM subjects.
He said: "I think the focus really is around the pattern of entry. I think that is the strongest thing that comes through. There is a real move towards maths and sciences."
Andrew Hall, chief executive of exam board AQA, said the drop in the number of people taking A-levels in modern foreign languages was "a real worry".
He said: "There is a crisis here in modern foreign languages. We have the euro economy in crisis - I think modern foreign languages are in the same place."
He said he was "quite worried" that the fall had been reported "year on year on year".
The number of grades awarded in French is down 5.2% from last year, and 13.6% since 2007 while German has seen a 7.6% drop, 24.3% since 2007. Spanish entries have fallen 3.4% from last year but increased overall by 5.8% since 2007.
Mr Hall asked: "Is this going to be like the euro, a risk of going into freefall?"
He said there was no "magic bullet" to fix the problem but said he was encouraged by the move to introduce modern languages in primary schools.
