Hamilton said there was nothing wrong with his car, but that he had not delivered "a good lap".
"The car has been OK this weekend," he said. "It was good in P1, and P2 was so-so. Today we made some improvements again.
"The car has been good and Nico was able to show that today. Hopefully from there he should be able to get a good result, and I have to push to get myself up into the top three."
Mercedes team principal Ross Brawn said he was not disappointed as the balance has always fluctuated between his evenly-matched drivers.
"When one of them gets a tiny advantage and gets ahead, it is very difficult to define," he said.
"I think Nico this weekend was perhaps a little bit happier with the balance, got the car where he wanted for qualifying and perhaps Lewis didn't.
"The differences are tiny. It is not one having a disaster and the other having a good day.
"It is just the normal variances you get - and quite frankly it is great to see both of them like that. If we have one driver dominating then it means the other one isn't doing very well.
"We have two drivers doing very well, so from the team perspective having two drivers push each other like that is exactly what we want.
"Both have the same equipment, both have a very good team of engineers and mechanics, and I would like to see it swing like that on a regular basis so we don't have a weak bit of the team."