Apple lost its High Court appeal over a ruling that the rival Samsung Galaxy tablet did not copy the iPad.
The world's two leading smartphone makers are fighting over patents, both for smartphones and for tablets, in courts around the world.
The Court of Appeal upheld its judgment that despite some similarities, Samsung did not infringe Apple's design, in part because its products were "not as cool" as the iPad.
The U.S. company was instructed to run ads saying the Korean company did not copy the iPad, both on its website and in selected newspapers.
Judge Kitchin said that the notices must be in a font size no smaller than Arial 14.