Hi Lazaros,
thank you for the answer!
I’ve thought about my question and in effect trying to filter LSPs inside of an area it does not really make sense: if I filter one LSP to be sent by a router, the neighboring router would not have the same LSDB of the others and this is a big problem in IS-IS/Link-State Routing Protocol.
Furthermore If I do not want some profixes to be present inside of an area database (L1 or L2) I simply do not enable the attached interface on the router and the prefix is actually filtered inside of an area/LSPDB-Lx without having to configure any kind of redistribution.
Is it right, no? 