Under the February 13 deal North Korea agreed to shut down its nuclear reactor at Yongbyon, as the first stage of a denuclearisation process and allow UN inspectors to return.
In exchange, the other parties to the deal - China, the US, Russia, Japan and South Korea - agreed to provide North Korea with economic aid and political concessions.
"It's important for North Korea to continue to respect its promises"
Chief spokesman Japanese cabinet
Shiozaki's comments come amid reports that South Korea is considering a suspension of rice aid to the North as a way of increasing pressure on Pyongyang.
"We can't just ignore and do nothing if ... North Korea doesn't take initial steps," an unnamed South Korean official told the Seoul-based daily Dong-a Ilbo on Monday.
Officials from North and South Korea are scheduled to begin talks on Wednesday in Pyongyang to discuss the North's request for 400,000 tonnes of rice.
South Korea periodically sends rice and fertiliser to the impoverished North, which has relied heavily on foreign handouts since famine first broke out in the mid-1990s leading to the deaths of as many as two million people.
North Korea had until Saturday to shut down its nuclear reactor, but failed to do so because of a delay in the release of its funds frozen in a Macau bank account.
The funds had been frozen following allegations from the US that the bank had been helping North Korean counterfeiting and money-laundering operations.
North Korea has said it will not take any further steps to disarm until all the funds are released.
On Sunday, the chief US nuclear negotiator with North Korea told reporters in Beijing that Washington would give the North a "few more days" to act.
"We're not happy that the [North] essentially has missed this very important deadline," Christopher Hill said.
"We're obviously going to be watching the situation very closely in the coming days."
North Korea itself has made no official comment since the deadline, with the country consumed on Sunday in celebrations of one of its main holidays: the birthday of Kim Il Sung, the country's late leader, known as the Day of the Sun.