U. S. District Judge Albert V. Byran Jr. yesterday rejected a prosecutor's request to order the jailing of a former U. S. Information Agency officer because he has been writing poetry to members of the jury that convicted him in 1978 of funneling classified documents to the Socialist Republic of Vietnam.

Judge Bryan ruled that Ronald Humphrey could remain free of $75,000 bond pending an appeal of his conviction, but ordered Humphrey -- who faces a 15-year prison term -- to have no further contact with jurors.

U. S. Attorney Justin Williams argued that Humphrey's recent letters to each of the 12 jurors in his case violated the terms of his bond and constituted harassment. According to court papers the letters contained poetry and an account of Humphrey's life since his conviction.

Humphrey's attorney, Warren L. Miller, told Bryan, who had received complaints from a juror, that his client would have "no further communication of any nature" with the jurors.

Last summer a federal appeals court upheld the convictions of Humphrey and his codefendant David Truong, a Vietnamese expatriot. The opinion left open the possibility of a new trial for the two men, a request on which Bryan has yet to rule.