North Korea may react to new sanctions with "further provocation," U.N. Ambassador Susan Rice said Friday after the Security Council passed a unanimous resolution condemning the communist country for recent rocket launches and a suspected underground nuclear test.

"There's reason to believe they may respond in an irresponsible fashion to this," she said. But she said she expects the sanctions to have significant impact on North Korea's financing of its weapons and missile systems.

Rice told reporters in the White House briefing room Friday that "we're very pleased" with the sanctions. And she called the new resolution, which was embraced by the U.N. with the support of China and Russia, an "unprecedented" position by the body.

Rice noted that the newly-passed resolution, among other things, would restrain North Korea's ability to export nuclear contraband. The sanctions expand an arms embargo and authorize ship searches on the high seas.

However, Rice said U.S. officials would seek permission to board and inspect ships believed to be carrying contraband and ships would be directed to a nearby port for inspection if they could not be boarded at sea.

Rice said that Iran -- another nation at deep odds with the United States about a disputed nuclear program -- should take a message from how the U.N. responded to North Korea's actions.

"I imagine that they have been following this closely," Rice said of Iran's leaders. She said Iran should see that "the response from the international community has been very clear, very firm and very meaningful."

The Associated Press contributed to this report.