I found out it was easy. just add this in style css
.Post-body img, .Post-body iframe {
max-width: 100%;
pointer-events: none;
}
Or you can use
a[href$=".png"], a[href$=".img"], a[href$=".jpg"], a[href$=".jpeg"] {
pointer-events: none;
}
Unselectable embedded image without clicks links or open new tab example