Hi @Narek_Antabyan,
The header for X-Frame-Options is set on your side and unfortunately, we can’t control these headers. You will have to disable the header if you want your content to be embedded inside the iframe.
For selectedIDs, as explained in the final reply of the other thread that you started, Pipedrive provides the context when the iframe request is made. There is no need to manually add it to the iframe configuration.