An American University poll of District of Columbia residents indicated that Mayor Marion Barry and former Carter cabinet secretary Patricia Roberts Harris were the leading Democratic candidates in the Sept. 14 primary.

Barry held a slight edge over Harris in the poll. He was the choice of 24 percent of the respondents, compared to 20 percent for Harris. Former City Council chairman Sterling Tucker, who has removed his name from contention, was chosen by 11 percent of the respondents.

City Council member John Ray (D-At Large) was chosen by 9 percent, Betty Ann Kane (D-At Large), 6 percent; John A. Wilson (D-Ward 2), 1 percent, and David A. Clarke (D-Ward 1), 1 percent.

Twenty-two percent said they were undecided and 7 percent said they would not vote for any of the candidates named in the poll.

The poll included both Republicans and Democrats, although Republicans will not be able to vote in the Democratic primary, so its results could at best be considered a reflection of the general sentiment of all voters in the city.

All the council members except for Clarke, who is expected to run for council chairman, have announced their candidacy for mayor. Council member Charlene Drew Jarvis (D-Ward 4), who launched her campaign last week, was not included in the poll of 241 persons taken by telephone Feb. 22 and 23.