The fine white dots on the leaf are sucking sites from spider mites which may or may not be there at this point. You need to look very close at the leaf to see them. They are often orange/tan in color, but not always.

Yup looks like spider mites. I've battled them several times.

Thanks. I looked very well and I didn’t see any thing specially in the underneath of the leafs.

Yesterday I started a treatment with Neem oil+ organic detergent with water. Is this ok?

that should work provided you sprayed upper/lower surfaces of leaves. if it is an active infestation you may have to do a few treatments.