Speaking Friday at the new Royal Marines Tamar base in Devonport, Plymouth, Harry told the wife of one of the Marines he's not rushing to give his father, Prince Charles, more grandchildren.
William's first son, Prince George Alexander Louis, was born July 22.
"No, he's got one [grandchild] now it will be fine. The pressure's off now," Harry said.
The prince was in Devonport to open the new $45 million base, which will be used for training hovercraft vehicles and for coastal and river landings, People magazine reported Friday.
While at the event, he visited with Marines and their families, including a 6-year-old identified only as Jacob, who showed the prince a drawing of the two of them on a Naval ship.
The drawing said "Dear Harry, you're fantastic."
Prince Harry responded to the boy, "It looks like you're driving."