A day after warning of an economic "D-Day" for Iran, Bessent said Washington would target entities that continue to facilitate financial transactions for Tehran.
"Any entity that facilitates money laundering on behalf of Iran will be removed from the US dollar system. The clock just started ticking," Bessent said at a news conference on Monday.
He said the US would pursue new sanctions aimed at cutting off potential sources of revenue for Iran.
Countries could face secondary sanctions
Bessent warned that countries that continue to maintain economic ties with Iran could also face US sanctions.
While he did not identify specific countries that could be targeted, he said it was "no longer acceptable to operate in the grey spaces" amid the ongoing conflict.
He added that countries refusing to join the US sanctions campaign would "share in the isolation" of Iran.
China, Turkey and UAE among Iran's key trade partners
China, Turkey and the United Arab Emirates are among Iran's largest trading partners, making them potentially significant players in the impact of Washington's expanded sanctions campaign.
The US has been seeking to tighten economic pressure on Tehran, particularly by targeting the flow of money generated from Iranian oil exports.
Oil revenue in US crosshairs
Responding to questions about the new sanctions, Bessent said entities involved in facilitating transactions or helping Iran convert oil revenues into usable funds would be targeted.
The latest measures are part of a broader US effort to restrict Iran's access to international financial markets and squeeze the revenue streams that support its economy.
Bessent's warning signals that Washington could widen the scope of its sanctions beyond Iranian entities to foreign companies, financial institutions and other parties that continue doing business with Tehran.