Two American journalists officially accused of writing slanderous news dispatches yesterday defended their articles as fair and proper to a Moscow city court judge. Later they denounced the proceeding against them and said they may not attend their trial next week.

Craig Whitney of The New York Times and Harold Piper of The Baltimore Sun issued the denunciation and notice of possible withdrawal as active participants after Lev Almazov, court president, complained about their conduct.

The judge also refused a two-week delay which the newsmen had sought to adequately prepare for a trial in the civil slander suit opened against them two days ago. The judge did move the trial back by two days, but the two correspondents refused to sign an official statement acknowledging the trial date.

Later, U.S. Ambassador Malcolm Toon joined the mounting tide of official American criticism of the Soviet move against the reporters. In a rare public accusation. Toon declared that the "principal motive" of Soviet authorities in engineering the suit is to intimidate American correspondents from reporting on the activities of dissidents, whom the Kremlin has long sought to suppress.

Whitney and Piper went to Almazov's office yesterday facing a 48-hour deadline expiring at noon for submitting detailed written responses to the bizarre slander suit and lists of prospective witnesses. They read the judge a short statement setting forth the need for more time and saying their dispatches were fair.

When they emerged after 25 minutes of what was clearly a strained meeting, they said Almazov was unmoved by Whitney's request for time to bring a lawyer and editor here from the United States for consultation, and that Almazov turned a deaf ear to Piper's request for a trial postponement until a recommended Moscow attorney finishes his vacation.

"I can't demand that you make use of your rights," they reported Almazov as replying to these requests. He then gave them until Monday for the detailed written documents and moved the trial back two days to July 7.

"I think they way in which our response was treated today raises serious doubts as to whether participation in the trial is at all advisable," Whitney declared afterward. "If we are not able to defend ourselves properly, then the aim of this trial is clearly not justice, or determination of fact, but some other obscure political purpose." Piper concurred.

Toon, speaking to American correspondents here, said: "The principal motive is to get a message across to you people - unless you confine your quotations to statements by Soviet officials, you run the serious risk of being tried for libel and slander. It seems a challenge to your past and current reporting on dissidents and refusedniks." The latter term refers to Jews refused permission to emigrate to Israel.

Western diplomatic sources here said they believed the two men should not appear in court.

"It will simply become a fishing expedition for a political trial," asserted one source.

Soviet civil law apparently provides for no criminal sanctions for defendants who refuse to participate in civil cases of this type. The two are clearly wary of doing anything that could be taken by authorities even now as willing participation in a process that many have warned them will disregard legal requirements and proceed to a finding of guilt regardless of their attempts to defend themselves or argue points of law.

Already, it was learned, the case against them has apparently violated two procedure points: the judge's deadline for written submissions is at variance with Soviet legal procedure as described in law books which asserts that a defendant can submit written documents at any time in the trial process.

The other apparent violation is that the suit names only the correspondents as defendants when the Presidium of the Supreme Soviet in an earlier domestic slander case required that the plaintiff name not simply a reporter, but an editor as well. The lawful remedy for a published slander here is published retraction and a reporter does not have the power in most cases to tell editors what to publish.

These two examples were being cited here last night by sources as evidence that the government is more interested in the verdict than other aspects of the case.

The suit was brought by the State Committee of Radio and Television, a government agency in charge of the broadcast media. It said articles the newsmen wrote last month "denigrated the honor and dignity" of its employes who prepared a televised confession of a convicted Georgian separatist and human rights activist.

The articles quoted unnamed dissidents in a nationalisti-minded Soviet Georgia as saying they believed the confession of Zviad Gamsakhurdia had been faked. The Soviets ascribe the views of the dissidents quoted in each article to the journalists themselves and demand a retraction.

The dispatches were printed in the Times and the Sun. which do not officially circulate here. However, the Voice of America and other foreign stations broadcast the accounts of the articles into the Soviet Union.

Whitney and Piper submitted virtually identical brief statements to A1-mazov yesterday defending their articles and questioning the legal basis of the suit, which seeks to apply Soviet civil law to foreign publications.

"Within the Soviet practice of not imposing censorship on dispatches sent abroad, I contend that I acted properly within the scope of my professional responsibilities in fairness both to my sources and to the authorities," the two declared.

Piper, who holds a law degree, added. "In general, states do not assert the right to control the content of information received by citizens of other states."

Piper, describing the middle-aged Al-mazov's manner as "very brusque," said the judge was displeased when the reporters told him they had not had time to meet his 48-hour deadline.

Through an interpreter from the Intourist travel agency protocol section, Andrei Sedrev, the judge asserted, "You put me in a rather awkward position. I'm accustomed to both parties in the proceedings observing the schedules set. Not only does your present action disrupt the court schedule, it disrupts my personal plans."

Piper said he replied, "The rights of defendants ought to have equal status with your personal plans."

They said the judge, looking irritated, retorted, "I'm obliged to take into account the interests of the defendants and the plantiffs. I'd like to meet your requirements. But last time you were here I read you a statement that you have not only rights, but obligations to the court and you must acquit yourselves according to these obligations."

Piper's request that the trial be postponed until July 17 until he could consult with attorney Genrikh Rubezhov was turned aside. The judge said there were many other qualified lawyers in Moscow. Then he reportedly said, "Well, I'can't demand that you make use of your rights."

The session ended with the newsmen refusing to sign a statement asserting the trial would be July 7, out of concern that it would be interpreted as agreement by them that they would be ready for trial that day. But they were not allowed to depart without signing something, so they put their signatures to a statement saying the court date was set without their agreement.

An American specialist in Soviet law, Leon Lipson of the Yale University Law School, was scheduled to arrive last night to begin consultations with Whitney and his bureau chief, David Shipler.

In a related swipe at American correspondents here, a Soviet newspaper accused Charles Bierbauer of ABC News of trying to disrupt a news conference by asking "provocative questions" of Mohammed Ali during the boxer's Russian tour last month. Bierbauer had challenged Ali's assertion that Moslems in the Soviet Union could freely practice their religion.