TEHRAN — Iran’s supreme leader said on Wednesday that his country should find internal solutions for dealing with economic sanctions and that the United States could not be trusted to lift sanctions in the event that a nuclear agreement is reached.

The leader, Ayatollah Ali Khamenei, reiterated in a speech published on his personal website that he did not oppose the current negotiations with the United States and other world powers over Iran’s nuclear program, but said that Iranians needed to rely on “bright and realistic glimmers of hope, and not on imaginary ones.”

Those talks are scheduled to resume Jan. 18 in Geneva, Iran’s state Islamic Republic News Agency reported on Tuesday.

Image Ayatollah Ali Khamenei, Iran’s supreme leader, speaking at his residence in Tehran on Wednesday. Credit... Office of the Iranian Supreme Leader, via Associated Press

In his first public criticism of the government of President Hassan Rouhani since his election in 2013, Mr. Khamenei said the government should “trust the people and domestic forces.” He also asked officials to refrain from “saying unnecessary words.”