The U.S. Treasury Department on Thursday blacklisted four foreign companies for allegedly supporting and facilitating Iran’s petrochemical and petroleum exports, among the latest efforts by Washington to ramp up pressure on Tehran.

The Treasury alleged the four companies, based in areas ranging from Hong Kong to Shanghai to Dubai, collectively ordered the transfer of the equivalent of hundreds of millions of dollars to the state-owned National Iranian Oil Co. as payment for Iranian exports.

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President Trump in 2018 authorized the Treasury to impose secondary sanctions related to the National Iranian Oil Co., which is on the U.S. blacklist as an entity controlled by the government of Iran. The U.S. said the company helps finance Iran’s Islamic Revolutionary Guard Corps- Qods Force and its proxies.

“This is simply another step in the economic terrorism the U.S. is engaging in against Iranians,” Alireza Miryousefi, the spokesman for Iran’s mission to the United Nations, said in an email. “It will not, however, bring any satisfaction to those looking to cripple the proud nation of Iran.”

The companies blacklisted Thursday include Hong Kong-based Triliance Petrochemical Co., a broker with branches in Iran, the United Arab Emirates and Germany; Hong Kong-based Sage Energy HK Ltd.; Shanghai-based Peakview Industry Co.; and Dubai-based Beneathco DMCC.

Triliance and Beneathco didn’t respond to requests for comment. Efforts to reach Sage Energy HK and Peakview Industry were unsuccessful.

The sanctions freeze assets held by the companies within U.S. jurisdictions and prohibit U.S.-based individuals and firms from doing business with the companies, unless permitted by Treasury’s Office of Foreign Assets Control.

The Trump administration expanded its sanctions campaign against Iran earlier this month in response to Tehran’s recent attacks against U.S. bases in the region after a U.S. airstrike ordered by Mr. Trump killed a top Iranian general.

Write to Mengqi Sun at mengqi.sun@wsj.com