North Korea test-fired only one missile on Friday rather than the multiple launches earlier reported, according to South Korean media reports.
One short-range missile was fired into the Sea of Japan, Yonhap quoted an intelligence official as saying.
But there were no launches off the west coast, the official told the agency.
However, a further test was possible, another source said, citing an ongoing ban on North Korean fishing boats from entering western coastal areas.
Both South Korea and the US have sought to play down Pyongyang's missile test, which coincided with the launch of South Korea's first destroyer equipped with US-supplied high-tech Aegis radar.
It comes more than a month past a deadline for North Korea to shut down its Yongbyong nuclear reactor under a deal designed to end its nuclear programme.
Initial reports from the region said that two or more anti-ship missiles were fired off North Korea's east and west coasts.
But some South Korean media reports now say that only one missile was fired. Daily JoongAng Ilbo said that the missile - a land-to-ship type called the Silkworm or HY-2 - landed 100km (62 miles) from North Korea's eastern coast.
The tests have drawn a muted response from the international community.
Japanese Prime Minister Shinzo Abe described North Korea's actions as "extremely regrettable", but said they did not constitute a serious threat to Japan's national security.
Opposition lawmakers in South Korea accused the North of piling on pressure ahead of inter-Korean talks on Tuesday where the issue of rice aid will be discussed.
White House spokesman Gordon Johndroe, meanwhile, said that the US viewed the action "as a routine exercise".
The State Department said that it would not affect the ongoing six-party disarmament process.
US officials are keen to move ahead with implementation of the landmark 13 February deal, under which North Korea agreed to begin scrapping its nuclear programme in return for economic and energy aid.
But a row over North Korean funds frozen in a Macau bank has delayed progress for several weeks, with North Korea refusing to move forward until its funds have been released.