Wednesday's firing of the missiles proved the country's nuclear programme posed a threat to the region, the White House said.
There were conflicting reports on the launch, with Japan's Kyodo news agency citing a security source in China as saying the missiles were fired by mistake in the direction of China during a military drill but landing inside North Korea.
The agency also cited a Western military source as saying the missiles were test-fired in an eastern direction from the North's eastern coast, towards the Sea of Japan.
The incident comes amid a stalemate in talks over the North Korean nuclear programme.
White House spokesman Scott McClellan said: "Indications are that North Korea launched two short-range missiles. The regime has conducted similar tests in the past.
"We have consistently pointed out that North Korea's missile programme is a concern that poses a threat to the region and the larger international community."
A senior Bush administration official said in Washington the two missiles were launched from North Korea and landed in the country. "They did not leave North Korean territory," he said.
Jack Pritchard of the Korea Economic Institute said this was "probably the third known incident of a short-range missile being fired over the last 18 months".
North Korea has abided by a 1999 moratorium on medium- and long-range missile tests.
US officials urged Pyongyang to resume six-party talks aimed at ending the communist state's nuclear programme. The United States, Russia, Japan, China and North and South Korea take part in the talks.
State Department spokesman Sean McCormack said those talks also provided a forum in which issues of missile proliferation and missile technology can be addressed.
The US has urged Pyongyang to
return to the negotiating table
"There are five other parties ready to come back, without precondition, and at an early date. We continue to encourage them (the North Koreans) to do so and to return to the talks without preconditions; to be ready to engage in serious negotiations."
Ri Gun, a senior North Korean official, was quoted by the Yonhap news agency as saying that North Korea would not return to the talks unless the United States ended its financial crackdown on Pyongyang's assets.
The US has cracked down on firms it suspects of aiding Pyongyang in illicit activities such as counterfeiting that it says help fund the North's nuclear programme.