"The most hated and sinister government in the world, which is the main source of wars, discord and plunder of nations, insults the noble people of Iran every day. However, the Iranian nation will not retreat," he said during a meeting with officials and members of the judiciary in Tehran, his website reported.
Ayatollah Khamenei noted that Washington's overtures are a "deception", meant to "disarm the nation" and "eliminate sources of Iran's power".
The Islamic Republic will continue on the path that it has chosen with "full force" and will achieve all its objectives, Financial Tribune quoted him as saying.
In an executive order on Monday, US President Donald Trump targeted the Leader and other top Iranian officials with sanctions, the impact of which has been played down by Iranian officials.
The sanctions followed Iran's downing last week of a US surveillance drone over the Strait of Hormuz, which it said had violated the country's airspace.
The incident further aggravated tensions sparked by Washington's unilateral decision to quit the international nuclear deal last year and reimpose sanctions on Iran.
Trump has coupled his "maximum pressure" campaign of sanctions with invitations to sit down with Iranian leaders.
Talks Offer Not Genuine
The Leader said the US offer to negotiate is not genuine and aimed at weakening Iran.
"Having failed to accomplish its goals through pressure, the enemy is offering to negotiate, assuming that the Iranian nation is simple-minded," he said.
"If we agree to their demands in negotiations, they will make the nation miserable. And if we don't, they will continue their political, propaganda and pressure campaigns," the Leader said, declaring that the US presence in Iran will hinder the country's progress.
Many political observers have raised doubts about the sincerity of the US administration's offer of dialogue with Iran, especially after the US recently imposed a spate of sanctions to save face after the fiasco of losing a Golden Hawk unmanned drone to Iranian air power.
According to one of the European nations attempting to mediate between the two sides, the United States is not serious about pursuing dialogue with Tehran despite Trump's insistence he is willing to sit down for talks.
However, French authorities, among other European nations, continue to search for a way to defuse growing tensions between the two arch-foes. Nevertheless, the French say they see "no signal the US is interested in dialogue", a defense source in Paris told CNN.