Three clergymen representing the Roman Catholic, Protestant and Jewish faiths were rebuffed at the Soviet Embassy yesterday when they attempted to deliver a letter protesting the treatment of Anatoly Scharansky and other Soviet dissidents.

The men spent less than four minutes inside the embassy and said afterward that Boris N. Davydov, a press attache, declined to accept the letter addressed to Ambassador Anatoly Dobrynin.

"He didn't explain," said Msgr. Francis Lally, representing the National Conference of Catholic Bishops. "He said he didn't wish to speak on the subject."

Rabbi Walter S. Wurzburger, vice president of the Synagogue Council of America, said the Soviet spokesman refused to discuss the recent trials of the dissidents on grounds it was an internal matter.

And Bishop James K. Mathews of the National Council of Churches of Christ said the clergymen were received "courteously, although coldly."

More than a half dozen clergy members approached the embassy to deliver the letter appealing "most earnestly" for the release of Scharansky, Vladimir Slepak, Alexander Ginzburg and Victoras Petkus, all convicted in recent days and given long prison sentences.

By prearrangement, only the three representatives were admitted.

After being rebuffed, the clergymen debated sliding the letter under the front door of the embassy. They decided instead to mail it.

"We fear a serious deterioration of the international climate, a development we are most anxious to avoid," the letter said.