Lebanon's military prosecutor reacted testily in an interview published here today to the unflattering comparisons by the international press of his still uncompleted inquiry into the Sabra and Shatila masacres with the exhaustive findings of Israel's special inquiry commission.

Assad Germanos, the prosecutor general, said he had not been able to work full-time on the investigation but expected to complete his work within 1 1/2 months. It will be up to the political authorities to decide whether the findings will be published, Germanos said in the interview in the English-language weekly Monday Morning.

"We were theoretically not the competent authority to launch an inquiry since Sabra and Shatila were under foreign occupation," he said. "In spite of this, and despite the fact that many of those who were killed were in Lebanon on an illegal basis, President Amin Gemayel ordered an inquiry."

"Let them stop comparing us with other inquiry commissions who sat behind their desks and had all the means at their disposal," Germanos said. "Let them give us more time."

The Israeli commission, headed by Chief Justice Yitzhak Kahan, blamed Christian Phalangist militiamen, Israel's allies here, for the massacre of the hundreds of Palestinian refugees in the camps in September. The report also placed indirect blame on Israeli military and political leaders since the camps were under the control of Israeli forces.

The release of the report had little effect here.

Although passing note was given to the commission's finding that the attackers were the still anonymous and unpunished Lebanese Phalangist militiamen, there was no discernible public outcry, except among Palestinian refugees.

Lebanese commentators tended rather to focus their attention on the possible impact of the domestic Israeli crisis on the current negotiations on withdrawing foreign troops from Lebanon.

But the Lebanese appear to have been stunned and humiliated by the subsequent international press comment giving Israel generous credit for conducting the inquiry, the speculation that the Lebanese will never make the results of their investigation known and comparisons like that made by the Economist of London likening the Phalangists to "angry wolves" let into the sheepfold.

Reflecting the new Lebanese concern, Foreign Minister Elie Salem said yesterday he had cabled Lebanese ambassadors abroad to clarify the stand of the Lebanese government on the Israeli report.

Local newspapers quoted Foreign Ministry sources as saying, "Lebanon does not consider itself concerned with what appeared in the report."

Privately, however, top government officials and religious and political leaders express concern about Lebanon's public image. And they plead for understanding.

As they attempt to explain themselves, they say the massacres were but a few hundred deaths in a nation where more than 100,000 have been slain during the past eight years of civil strife. Christians have been pitted against Moslems--including large numbers of Palestinians who came here as they were forced out of their homes elsewhere--and Syrian troops, who came here as peace-keeping forces.

Lebanese, these government, political and religious leaders say, are not interested in pinning blame but rather are weary of the unbroken chain of violence followed by revenge and are eager that it be ended.

In the Monday Morning interview, Germanos indicated that much of his time was devoted to investigating the still frequent violence.

He said he believed that the amount of violence had been reduced by 80 percent since September and that Lebanon is now going through the "end of the nightmare." But he said Army intelligence has determined that 20 booby-trapped cars have been brought into Beirut in recent weeks.

"You know the people behind these bombs and the others we have discovered as well as I do," Germanos told his Lebanese interviewer. "For eight years you and I have lived among them. They are all the foreigners . . . and all the Lebanese associated with those foreigners--who have taken advantage of instability in this country and want that instability to continue."

Germanos said he meant the Israelis, Syrians and Palestinians here.

What is new in the wake of the commission report is that the Lebanese Christians, once Israel's allies, are growing cool toward Israel.

Moslem leaders say they believe Israel's mistake has been to leave the Christians feeling humiliated.

It is for this reason, the Moslem leaders say, that they have been circumspect in their response to the findings of the Israeli commission and avoided blanket condemnation of the Phalangists for the massacres.