Not ethical behavior

Quite a while ago I played in a chess tournament. It was my second real chess tournament in my life(that's why I'm quite ignorant about not-quite-chess rules). I was low on points, so I was really eager to win one more game. My opponent was CM(I learned about it after the game). He made moves very quickly and soon blundered a whole exchange, only compensation being his two bishops. I considered my position won and I wanted just to lead the game safely to my win. But I got nervous, made some mistakes, get into timetrouble. The game became very sharp with my opponent's attack on my king. After one of my move my opponent said to me: oh you just could've played that move and win my rook and the game. I asked why did he told me about. He just grinned. He was pleased, of course. I was furious at him seeing that my position is bad or even losing, there were no good moves. After two moves I resigned. I was furious at myself and my opponent. So my question is. Are there any rules that regulate such behavior of opponents?

I suppose you could claim that he was trying to distract you and could have made a complaint to the tournament director. But I doubt any of them would have done anything in your favor other than asking your opponent to refrain from making further comments.

I have been a tournament director (and arbiter) in the USA, whose rules are slightly different than FIDE, so I'm not sure an FIDE TD/arbiter would have reacted the same way.  No one is allowed to comment on a live game and mentioning what you should have done can potentially help you evaluate the current position and is therefore against the rules.  I would have ended the game and given you the win if you had enough material on the board to make a checkmate, otherwise a draw, because he violated the rules while it was being played.

Thanks for answer! One more question. In such a situation how can I prove that my opponent has said something to me? It's my word against his, isn't it?

Exactly right, which is one reason why these rules aren't often strictly enforced.   More importantly, directors want games to be played out and do not wish to invoke the ultimate penalty unless the most severe circumstances exist.  I played in more than a hundred tournaments and I never saw anyone award a game on a first offense because of an ill-timed comment by an opponent. 

from a discussion on the USCF Forums:

 

5th Edition rules, page 83 wrote:20G. Annoying behavior prohibited It is forbidden to distract or annoy the opponent in any manner whatsoever. A director, upon a complaint by the opponent, has discretion to determine whether any particular behavior is in violation of this rule and to impose penalties.
20G1. Inadvertent annoying behavior. Sometimes a player's actions, though annoying to the opponent and possibly others, are clearly unintentional. For instance, a player may occasionally cough. While the director has the right to invoke rule 20G, this is quite harsh if the player's actions are involuntary. A partial solution is to assign such a player to a board in another room or far away from other games.
{TD Tips and See Also References above omitted}

In short, the TD gets to decide if the behavior is annoying at all, and if so what the appropriate penalty is from a warning to the standard penalty, up to a game or tournament forfeiture. The TD can, theoretically, upon a first offense and a complaint tell the other player, "You forfeit and are gone... here's your entry fee and now get off my playing site." I can't conceive of the circumstance in which any sane TD would do that. The TD would most likely thus buy an office complaint that would probably be righteous. But the power is there.

It is far more common for the TD, if the TD agrees the behavior is indeed annoying or distracting, to simply warn the other player to not do whatever it was. Maybe on a second offense the director applies a penalty, or gives another warning, or gives a 'final warning.'

I remember being in a similar situation, getting my backside handed to me game after game in a tournament and wondering if maybe golf wouldn't be less frustrating. Final game of the tourney, I was white, stronger player was black. I do the Scotch Gambit, just looking for a sharp position, put my opponent off guard. Five moves in, he says, "Oh, you're trying a different version of the Scotch." Now, I couldn't tell if he was trying to throw me off, if he was mocking me, if he was just making an observation or making conversation. I do know I wasn't in the mood to guess his intent, even though I took thirty seconds of game clock time to do exactly that. So I said, how about we both shut the hell up and just play? And the moment I said that, I could tell he was just trying to be a cool guy and make a little harmless conversation. So now, I'm feeling like a total tool and fixating on whether I offended the guy which led to me getting increasingly ticked off at myself and ticked at the guy for being ticked off, if he actually was ticked off. I blundered twice, lost the game. 

My point being, I can be an insecure child when playing chess. Carry on. 

The tournaments I've attended tend to have different rules but usually, talking during a game isn't allowed - unless someone's pointing out an illegal move or saying check or checkmate. I did have one guy that complimented me every time I made a good move, and another insisted on chuckling every time I made a not-so good one. You just have to keep going and block it out and try to keep going. I understand how annoying it can be...

Technically it's against the rules, but from my experience only a warning would be handed out instead of any kind of actual punishment unless the player keeps commenting and receives another warning or two. So I'm not sure what you could do about it...

You know, this conversation is bringing up another question--what *is* the penalty, short of forfeit? you mentioned a time penalty. That's a consequence in tournaments? Have you seen people penalized time-wise? This is very interesting to me. Looks like it'd be a good punishment.