Defense attorneys continued to attack the government's conduct in the Abscam bribery investigation in federal court today, focusing on the actions of Melvin Weinberg, a convicted confidence man who is the prosecution's star undercover witness.

Lawyers for four members of Congress and four others indicted in the FBI "sting" operation charged that Weinberg has conspired with FBI agents and prosecutors to create crimes to lure public officials, had lied repeatedly in a similar pretrial hearing in Philadelphia this week, and had a motive to leak the investigation tot he new media because he planned to write a book about his role in it.

The lawyers are arguing that the government's conduct in the case is so bad that U.S. District Court Judge Jacob Mishler should take the rare step of dismissing the indictments to punish the Justice Department and further deter such misconduct.

Mishler did not rule on the misconduct motion but made it clear he was concerned about the allegations that the government created the crimes. He said he was less impressed with the defense argruments that massive pre-indictment "leaks" to the press may have prejudiced grand jurors.

Mishler is the trial judge on three different Abscam cases involving the eight defendants represented yesterday, including Reps. John M. Murphy (D-N.Y.), Frank Thompson Jr. (D-N.J.), and Michael O. Myers and Raymond F. Lederer, both Philadelphia Democrats. Myers' trial is scheduled first, for Aug. 11.

Before the hearing, Murphy talked to reporters on the courthouse steps and charged that he was targeted in the investigation because his anti-communist views on foreign policy were in sharp contrast to those of the Carter administration.

Mishler later set a Sept. 2 trial date for the case against Murphy, Thompson and their codefendants. The judge also signed a protective order the prosecution requested to prevent public showing of the video tapes involving Murphy. Murphy's attorneys objected strenuously.

The defense attorneys spent much of their time today telling Mishler about the damage they feel they have done to the government's credibility in the Philadelphia pretrial hearings before Judge John P. Fullam."This investigation smells and the smell has affected Judge Fullam's courtroom," said Richard Ben-Veniste, attorney for Howard L. Criden, a Philadelphia lawyer who has been indicted four times so far for his alleged role as middle-man in the investigation.

Ben-Veniste and John J. Duffy, representing Philadelphia City Councilman Louis Johanson, outlined portions of the Philadelphia testimony which they said showed the government's misconduct.

For instance it was brought out there that both Weinberg and Neil Welch, the recently retired head of the FBI's New York office, plan to write books. While Welch testified earlier this week that Abscam would only be a footnote in his memoirs, a publishing executive testified yesterday that Welch's agent peddled the proposal as the inside story of Abscam and even mailed him press clippins noting Welch's role as evidence.

They also told Mishler how Weinberg's testimony was contradicted several times Thursday by Robert W. Greene, an editor at Newsday, who said he had talked to Weinberg about a book and about Abscam.

Michael Tigar, representing Murphy, said that the Philadelphia proceedings were showing that Weinberg "is fraud, his testimony is not to be believed."

James Binns, Lederer's attorney, said that his review of some of the Abscam tapes showed that Weinberg and the FBI plotted to go after public officials. "We want people with titles," was one remark heard on the tapes, he said, and he stated that the tapes referred to efforts to bring Philadelphia Major William Green and Rep. James A. Mattox (D-Tex.) into the Abscam net.

While it therefore appears that some targets were being preselected, others were rejected, Binns said, citing a tape in which a middleman tells the undercover agents that a certain congressman "is ready to go and I can get you 10 others." That claim was never followed up, he said.

In response to the defense claims of government misconduct, Thomas P. Puccio, the chief prosecutor in the case, told the judge he was confident that the trial would show that the middlemen, not the government, initiated the criminal activity alleged in the indictments.

Ben-Veniste claimed that the "scam" was continuing, with the American public and the judicial system being the targets. He accused the government of lying in court papers in Philadelphia when its attorneys said they didn't know the source of Abscam leaks. The two top prosecutors in Philadelphia acknowledged there this week that they disclosed parts of the investigation to local reporters.

Ben-Veniste also took issue with pronouncements by ranking government officials, including Philip B. Heymann, head of the Justice Department's criminal division, and FBI Director William H. Webster, that special precautions were taken to avoid entrapping innocent victims.

As the hearing started, Mishler signed an order giving the House Committee on Standards of Official Conduct access to the tapes of the indicted House members, over the strenuous objections of their attorneys. The lawyers said they feared the committee might make the tapes public before the trials.

But E. Barrett Prettyman Jr., the committee's special counsel, assured the judge this wouldn't happen unless the committee felt the cases were deliberately being delayed.