The dual actions were announced by the Departments of State and Treasury as Trump continued predecessor president Barack Obama's pact under which Iran agreed to limit its nuclear program in return for sanctions relief, Reuters reported on Thursday.
While Trump criticized the nuclear agreement as a presidential candidate – at one point saying he would "dismantle the disastrous deal with Iran" – the actions demonstrated that he has decided to keep it.
"The United States continues to waive sanctions as required to continue implementing US sanctions-lifting commitments in the Joint Comprehensive Plan of Action," the State Department said in a statement, referring to the deal by its formal name.
Separately, the Treasury Department said it had sanctioned two senior Iranian defense officials, an Iranian company, a Chinese man and three Chinese companies for supporting Iran's ballistic missile program.
The designation of the seven Iranian and Chinese people and companies blocks any assets they might have in the United States and bars Americans and non-Americans from doing business with them, at the risk of being blacklisted by the United States.
The United States on Wednesday renewed a waiver of the key sanctions that it imposed on Iran before the nuclear deal was ultimately struck.
Under these sanctions, tucked into Section 1245 of the 2012 National Defense Authorization Act, the United States threatened to sanction the banks of Iran's main oil customers if they did not significantly reduce their purchases of Iranian crude.
Under the law, these sanctions can be waived for a maximum of 120 days. The Obama administration did so in mid January, forcing the Trump administration to decide by Wednesday whether to renew them or to put the wider Iran deal at risk.
Richard Nephew, a former US negotiator with Iran now at Columbia University, called the renewal an "important step" in maintaining the deal but said it was still threatened by "congressional pressure, Republican politics, and the views of many people" in the Trump administration.
US ‘ill will’
Iran reacted to the new US sanctions targeting its ballistic missile program, saying the move shows Washington's "ill will" and could undermine the nuclear deal.
"Iran condemns America's unacceptable ill will in its effort to undermine the positive outcome of Tehran's commitment to implement the nuclear deal by adding individuals to its list of unilateral and illegal sanctions," Foreign Ministry spokesman Bahram Qassemi said on Thursday.
Echoing Iran’s official stance, Qassemi said Iran’s ballistic missile program was no breach of the nuclear deal.
"Iran will continue its missile program forcefully… as planned," he said.
In retaliation for the new US sanctions, Iran said it had added nine American individuals and companies to its own list of 15 US companies for human rights violations and cooperation with Israel.