I would suggest you look at the curled leaves using a good magnifying glass. Various types of aphid can give rise to a similar effect, and you will probably be able to see more clearly what is happening. It will make any internet search much easier.
If you can get a magnification lens for a phone or camera try a picture and post it here. There are plenty of knowledgeable people here, but on its own "leaf curl" is too broad a description for an exact diagnosis. I have some leaf curl on one apple tree but I have checked and in my case it is aphids.