Lawyers for a Cambodian woman arrested while demonstrating outside the Soviet Embassy argued in D.C. Superior Court yesterday that she had been "singled out" for prosecution, while more than 1,680 apartheid protesters, charged with the same crime outside the South African Embassy, have not been prosecuted.

Lawyers for a conservative public interest law firm, who represent Vanna Om Strinko, have subpoenaed U.S. Attorney Joseph E. diGenova to testify in court. They maintain that the choice was made because her "anti-Soviet criticism" is viewed as conservative, while the South African protest by "celebrities and liberal politicians" is a more popular cause in the District.

Government attorneys sought at yesterday's hearing to block the subpoena and argued that prosecutors have "wide latitude" in deciding who to prosecute after weighing many factors. They argued that Strinko's attorneys have fallen far short of proving there was any discrimination behind the decision to prosecute in her case.

At issue is a D.C. statute that makes it illegal to "congregate" within 500 feet of an embassy.

Hundreds of apartheid protesters, including members of Congress, entertainers and Effi Barry, the wife of Mayor Marion Barry, have been arrested under that statute since protests began outside the South Africa Embassy last Nov. 21.

However, after the first few arrests diGenova dropped the charges, and sources close to the office said he was not anxious to clog the District's overcrowded courtrooms with defendants arrested in symbolic, nonviolent protests.

Ironically, Rep. George W. Crockett Jr. (D-Michigan), one of those arrested, attacked diGenova for failing to prosecute, charging that the action was "part of an effort by the Reagan administration . . . to belittle the importance" of the protesters' cause by denying them their day in court. DiGenova denied that accusation.

Yesterday, Paul D. Kamenar, of the Washington Legal Foundation, argued just the opposite -- that diGenova's decision to prosecute Strinko was based on her views, considered politically conservative. Strinko was arrested Jan. 28 when she stood in silent protest in front of the Soviet Embassy after trying to deliver a petition attacking Soviet actions in Cambodia.

Kamenar also attacked the constitutionality of the statute, arguing that making it illegal to "congregate" within 500 feet of an embassy is an "overbroad" restriction of the First Amendment right to free speech. It also unconstitutionally gives "police officers unfettered discretion to disperse any congregation at their whim" without any guidance.

Assistant U.S. attorneys Craig Lawrence and Suzanne Curt, defending the statute, argued that there is a "compelling government interest" in creating the statute to protect foreign missions here.

"This is not a time to signal foreign governments and terrorists that the U.S. government will not stand foursquare behind the security of embassies," Lawrence told Superior Court Judge Warren King.

The judge took the case and the request for subpoenas under advisement.