Iran’s supreme leader, Ayatollah Ali Khamenei, rejected any idea of bilateral talks with the United States on Thursday in a speech in which he scoffed at Iranian officials who might consider such negotiations.

A staunch ideologue who has often rejected dialogue with America, Ayatollah Khamenei was apparently responding to a United States offer of one-on-one negotiations between the two countries on a range of topics, including Iran’s disputed nuclear program, a suggestion that Vice President Joseph R. Biden Jr. reinforced last week during a security conference in Munich. The Iranian foreign minister said then he was open to such talks, although Mr. Biden noted that they could proceed only if the ayatollah showed serious interest.