Ever seen a grown man naked?

For me, in a job interview, the last time it was pointed out that I was nervous, I failed the interview because of it. Their argument was that I had to be able to cope with the pressure of the environment, and that nervous people would not be able to. So your interviewer may not have been trying to reassure you, so much as verifying their assessment of you.

You may have been better off saying "I'm actually shaking because it's really cold in here".

Which is all very well, but why were you nervous?

WOW, these people are out line. Instead of pointing out you are a normal human being who cares about his life and lacks a little bit of confidence like there is something seriously wrong with you, they should of been asking you about work related stuff. I highly doubt most tweaked out meth heads are interested in being employed. A lot of people say that instead of making money, they like to take care of their basic needs with five fingered discounts. Not 100% sure though because I keep my distance from these people.
Seeing if someone is nervous during an interview is a horrible way to see if someone can cope with pressure. You failed the interview for a stupid reason.

Yeah, but seing if you are able of coping with the question itself (i.e. "OK, he's nervous, but will it make him a wreck when I point it out to him, or will he be able to come up with an answer?") may be a better way of assessing your "coolness under fire" ability

In my opinion there are three options:

1. This very person was never in your position (nervous) and he/she just can't comprehend your feelings. He/she thought that it may ease your level of discomfort due to lack of knowledge or psychology expertise > very odd for recruitment staff. Example: "You seem tense, don't be". This may only worse the situation for a person being tense.

2. This very person knows exactly what it's like to be in your position, he/she been treated that way in the past, may even be emotionally harassed by others. Deep down this person is hurting and it order to ease his/her own pain the "best" approach is to attack the other person in that same situation. As an example you may find lots of people who likes to criticize others or make fun of people around them but on the other hand hating being treated that way.

3. He/she is a stupid arrogant bitch ;)))

What person isn't nervous during a job interview? You find a person who's calm as a cup of water on a job interview, and I'll show you a person who raided a medicine cabinet before leaving the house first.

What's weird is that they seem surprised at someone being nervous even when the situation calls for it.
I always get the feeling that people who call others out for something are not that good at empathizing with people.
If were to interview someone for a job I would expect them to be nervous, because I can empathize with their situation.

Two aspects to this: he says that he sees that you're nervous, and wants to understand why. He expects a response. How you respond would affect his evaluation of you.

I usually answer something like: "I'm usually nervous in situations like this." I interview for a technical job (software developer), and it's not usually a requirement of such a job to be confident in various social situations such as a job interview. On the other hand it can help explain a lower than expected result of the interview (compared to your credentials, for example). I've been asked that and I don't think it ever hurt my chance.

Just tell them "Me? <slight chuckle>, no I'm not nervous, I've just got the meth jitters." then when they give you the "what the?" look, crack a smile ... "just messing with you". It's a real ice breaker! :)

"No, I'm not nervous. I used to be nervous during job interviews, but nowadays I do them so often I've grown so used to them that it feels as if something's wrong whenever I'm not in yet another job interview."