House Speaker Thomas P. (Tip) O'Neill Jr. said yesterday that he sent a strong personal message to the president of South Korea last week, warning that U.S. aid would be cut off unless accused Korean agent Tongsun Park is made available now to House investigators.

In an appearance on "Face the Nation" (CBS, WTOP), O'Neill said he sent for Korean Ambassador Yong Sitik Kim Wedesday. He said he told the ambassador to tell President Park Chung Hee of South Korea that "unless he (Tongsun Park) returns, you're in dire trouble."

"I don't think we could get an arms bill or a mutual aid bill through to help Korea unless they agree," he said later in the interview.

Tongsun Park, who has been indicted on charges of conspiring to bribe members of Congress, has been undergoing questioning in Seoul by a team of Justice Department prosecutors. But the Korean government has resisted making him available to the House Committee on Standards of Official Conduct, which is conducting a parallel investigation.

O'Neill said he had made it clear to the Korean ambassador that there was a "big difference" between the House and Justice Department investigations. "We're interested in the ethics of the House. We have to clean up our own name," O'Neill said he told the ambassador.

Leon Jaworski, special counsel to the House committee, said Friday that his investigation would be incomplete without testimony of Park and several other Korean witnesses, including former Ambassador Kim Dong Jo.

Citing the Korean government's reluctance, Jaworski recommended that the House pass a resolution linking continued U.S. aid to Korea to that government's cooperation. O'Neill quickly endorsed that idea, but his comments yesterday showed his personal interest in the matter ran far deeper.

An O'Neill aide said later that though the House Speaker mentioned only Tongsun Park in his talk with the Korean ambassador, he also supported Jaworski's demands for the other witnesses.

O'Neill has been the subject of scrutiny by House investigators because of his social relationship with Tongsun Park. The Massachusetts Democrat was a guest of honor at elaborate birthday parties Park sponsored for him in 1973 and 1974.

O'Neill repeated yesterday that he never talked about Korea with Park and that he attended the parties only because he was urged to do so by others. He noted that at one of the parties (the 1973 affair), five members of the cabinet, 18 members of Congress and then-Vice President Gerald R. Ford attended. "How do you turn down a party of that type?" he asked.

O'Neill said yesterday that he told the ambassador he wanted Tongsun Park "to come over with open arms and to testify before the ethics committee" before March 20. That is the expected trial date for former Rep. Richard T. Hanna (D-Calif.), the only member indicted so far in connection with the alleged Korean lobbying campaign.

The House committee has threatened to subpoena Tongsun Park when he returns to appear as a witness in that trial. Peter A. White, Jaworski's deputy, said yesterday that the committee is not willing to make an agreement limiting its questioning of Park in any way. "We'd like very much to get him now," White said, "but if we have to we'll wait and subpoena him."