North Korea wants to open a dialogue with the United States and "will keep knocking at the door." President Kim IL Sung said in a television interview broadcast today.

The North Korea leader called President Carter's plan to withdraw U.S. ground forces from South Korea "a very good thing" that removes a major obstacle to reunification of the Korean peninsula. Although he criticized Carter's intention to leave U.S. Air Force units in South Korea and the continuing American support for the Seoul government, his comments were moderate in tone.

The interview was aired in prime time by Japan's semi-governmental broadcasting corporation. North Korean sources in Tokyo later emphasized the friendly nature of Kim's remarks about the United States. If Secretary of State Cyrus Vance were authorized to visit Pyongyang, the North Korean capital, during his coming trip to Peking, he would be welcome, the sources said.

The Japanese television crew interviewed Kim at length June 3 during a two-week visit to a country that commentator Akira Ogata described as "unknown and mysterious to many Japanese." The 40-minute program included street scenes in Pyongyang, views of a tractor factory and shots of a rally where a crowd of 200,000 thunderously chanted a demand that the United States get out of South Korea.

Kim appeared to be in good health and in a relaxed, expansive mood. He chain-smoked cigars lighted by an aide, toyed with horn-rimmed glasses and frequently ended his gravel-voiced responses by beaming directly at the camera.

Neither the United States nor Japan has diplomatic relations with North Korea. Japan, however, which has trade relations with Pyongyang and has 300,000 North Korean residents maintains intermittent contact. The North Korean president's message seemed aimed more at Washington than at Tokyo.

North Korea proposed a dialogue to the United States "quite a long time ago," Kim noted. He said that although there had been no response, he stood ready to meet with American diplomats at any time.

U.S. policy, frequently stated, is that there will be no talks with North Korea unless South Korea is recognized by the North and included. Former Secretary of State Henry Kissinger accused North Korea of trying to drive a wedge between Washington and Seoul.

In tonight's interview, Kim complained that Carter's pledge on troop withdrawal differs from practice. American air force units are part of the foreign force stationed south of the demilitarized zone and should also be removed, he said. The timing of the troop pullout over four to five years left him uncertain whether Carter intends to complete the plan within his four-year term of office, Kim added.

Repression of human rights in South Korea is an obstacle to reunification, he said, yet Carter had not criticized the present government and is still giving aid.

"We hope and expect to reunify Korea peacefully," Kim said. "This is what all the Korean people hope for." He added that reunification would maintain peace in Asia, while the continued division of the two Koreas would perpetuate tension.

Kim's invitation to Washington intensified the friendship offensive he has mounted since Carter took office. Pyongyang has largely dropped the use of such hostile phrases as "U.S. imperialists" and appears eager to exploit the present cool relations between the United States and South Korea, caused by the troop-withdrawal plan.

The Japanese broadcast no balancing commentary on the reasons behind the failure of the United States and North Korea to normalize relations, and the North Korean president was not questioned about human rights in his own country. Kim therefore was able toportray himself as a calm, benevolent and eminently reasonable man.