Hitler did attack the US in WWII. During the first few months of 1942 his u-boats sank hundreds of ships (belonging to the US and her allies) just off our eastern coast. Many of the ships were sunk within view of people on shore. The Gremans even landed men on our shores (a couple landed in the north and another two landed in Florida) with instructions to blow up vital targets. Those guys either gave themselves up or were captured before they could do any damage.
The hundreds of ships those u-boats sank and the men lost on those ships wound up causing as much if not more damage to the US as the Pearl Harbor attack. The reason we didn't feel it as much is because it took place over a period of time and not all on one day like the Pearl Harbor attack.