I know many people, including myself who do the whole "Oh I love you" thing while drunk. It never bothers anyone since i've only ever said it to my boyfriend or to a close friend. But a lot of people do it, and it's just drunken, nothing that should be taken too seriously.
Just say you were drunk, you were being friendly, whatever. That's all it was and if he wants to believe otherwise then there is nothing you can do i'm afraid. He'll stop avoiding you eventually i'm sure, hopefully things wont be too awkward but it's I do find it slightly odd that he is taking it so seriously. Most people know that when people are drunk, most of the things they say are just the result of the alcohol, nothing more, nothing less. Give him time, he'll come round.