Japan's government says it has begun work on its own set of sanctions on North Korea, in addition to those agreed by the UN Security Council.
Mr Abe said the measures would include a ban on remittances
Chief Cabinet Secretary Shinzo Abe says he has instructed officials to put in place procedures to ban cash remittances to the impoverished North.
After days of talks the UN Security Council unanimously passed a resolution on Saturday which condemned the tests.
But it was a milder document than Japan's original draft.
The resolution was tabled in response to North Korea's decision to test-fire seven missiles earlier this month, including a long-range Taepodong-2, which is believed capable of reaching Alaska.
In the immediate aftermath of the test-firings, Japan imposed limited sanctions against North Korea, including a decision to ban a North Korean trade ferry from Japanese ports and a moratorium on charter flights from Pyongyang.
But now Chief Cabinet Secretary Shinzo Abe has asked for an investigation into possible further sanctions.
"We have started preparations to properly achieve necessary steps involving financial restrictions," Mr Abe told a news conference on Tuesday, although he added that Japan would consult with other nations before making a final decision.
He said he had instructed officials to start procedures to ban cash remittances by Koreans living in Japan who are sympathetic towards Kim Jong-il's government - an important source of foreign currency for North Koreans.
North Korea had been observing a missile-test moratorium before July
Indications that Tokyo was about to take further steps against Pyongyang were reported in Japanese media on Monday, but now Mr Abe has made his intentions official in a press conference.
Japan could also place bans on bilateral trade and freeze North Korean assets, according to the newspaper reports.
Japan is one of North Korea's most vehement critics - and takes a more hardline stance on Pyongyang's activities than other countries in the region.
Chapter Seven dropped
The UN resolution passed over the weekend demands that North Korea suspend its ballistic missile programme, and bars all UN member states from supplying Pyongyang with material related to missiles.
It was passed unanimously by the Security Council after being revised to drop any mention of Chapter Seven of the UN Charter, which is legally binding and can authorise military action. The changes were made to appease China and Russia, which took a softer line than Japan and the US. China had threatened to veto the resolution in its original form.
As soon as the resolution was passed, North Korea's ambassador to the UN rejected it and left the chamber.
A day later Pyongyang angrily denounced the resolution in a foreign ministry statement, and said it would continue to build up its military arsenal.
The statement described the resolution as the product of a hostile American policy and said Pyongyang would not be bound by it, and would "bolster its war deterrent" in every way.