DALLAS (AP) — American Airlines is planning to drop flights to up to 30 smaller U.S. cities if a federal requirement to continue those flights expires at the end of next month, an airline executive familiar with the matter said Thursday.

American agreed to keep serving those smaller cities as a condition of receiving $5.8 billion in federal payroll help this spring. However, the money and the requirement to serve those destinations both expire Sept. 30 unless they are extended.

The move by American could put more pressure on Congress and the White House to give passenger airlines another $25 b...