At a Camp David news conference, Mr. Bush said he remains committed to a diplomatic solution, but warned that if North Korea remains obstinate it will have "a price to pay," reports CBS News White House correspondent Mark Knoller.
"Our partners in the six-party talks are patient, but our patience is not unlimited," Mr. Bush said, referring to disarmament negotiations between the United States, Japan, China, Russia, South Korea and North Korea
For his part, Prime Minister Shinzo Abe said, "We completely see eye to eye on this matter. They need to respond properly on these issues. Otherwise we will have to take a tougher response on our on our side."
North Korea missed a deadline to shut down its nuclear reactor under an agreement reached in February.
Mr. Bush's words appeared to be an attempt to persuade Abe that the United States is not softening its stance on North Korea, as some in Japan have suggested.
Japan is already withholding economic and food aid to the reclusive communist regime.
Abe said that sanctions "will worsen" if North Korea continues to defy the international community.
On another subject, Abe apologized for the Japanese military's actions in forcing women to work in military brothels during World War II. He said he wanted to "express my apologies that they were placed in that circumstance."
Abe created a controversy recently by suggesting their was no evidence Japan's Imperial Army had directly coerced the so-called "comfort women" to work in brothels.
In his Camp David remarks, Abe said he had apologized for those remarks in his meetings with members of Congress on Thursday, and again with Mr. Bush on Friday.
Mr. Bush said the comfort women situation was "a regrettable chapter in the history of the world. And I accept the prime minister's apology."
Abe expressed "deep-hearted sympathies" for the comfort women, saying they had been placed "in extreme hardship."
At the same time, Abe said that "human rights were violated in many parts of the world" at the time. "So we have to make the 21st century a century in which no human rights are violated," he said. He pledged to make "a significant contribution to this end."
On the North Korea issue, Mr. Bush said, "We expect North Korea to meet all its commitments under the Feb. 13 agreement. And we will continue working closely with our partners."
A U.S. decision to allow the return of $25 million in disputed North Korean money in an attempt to move the disarmament process forward has been criticized in Japan as a sign of softness.
Mr. Bush addressed this issue. "There's a financial arrangement that we're now trying to clarify for the North Koreans, so that that will enable them to have no excuse for moving forward. And that's where we are right now," he said.
"I think it's wise to show the North Korean leader as well that there's a better way forward. I wouldn't call that soft," said Mr. Bush.
On another nuclear weapons issue, Mr. Bush also said that "we speak with one voice to the regime in Iran. Our nations have fully implemented the sanctions imposed by the U.N. Security Council in response to Iran's pursuit of nuclear weapons.
"Further defiance by Iran will only lead to additional sanctions and to further isolation from the international community," Mr. Bush said.
The leaders of the world's two largest economies also discussed trade, encouraging use of biofuels, the Iraq war, and Japan's continued restrictions on U.S. beef imports because of a perceived danger of mad cow disease.
"One such issue, of course, I brought up to the prime minister is I'm absolutely convinced the Japanese people will be better off when they eat American beef. It's good beef. It's healthy beef. As a matter of fact, I'm going to feed the prime minister and his delegation a good hamburger today for lunch," Mr. Bush said.
Abe's two-day U.S. visit was his first since becoming prime minister in September.