The United States has unveiled new economic sanctions against Iran over its ballistic missile program and for contributing to regional tensions and said it was deeply concerned about its "malign activities across the Middle East."

The announcements came a day after President Donald Trump's administration warned Tehran that it was not following the spirit of its 2015 nuclear agreement with world powers.

The US Department of Treasury said in a statement it was targeting 16 entities and individuals for supporting what is said was "illicit Iranian actors or transnational criminal activity."

Those sanctioned had backed Iran's military or Iran’s Islamic Revolutionary Guard Corps (IRGC) by developing drones and military equipment, producing and maintaining boats, and procuring electronic components, it said. Others had "orchestrated the theft of US and Western software programs" sold to Iran's government, the Treasury Department said.

The US State Department had also designated two Iranian organisations involved in Iran’s ballistic missile program, according to the Treasury Department.

"The United States remains deeply concerned about Iran’s malign activities across the Middle East which undermine regional stability, security, and prosperity," the State Department said in a statement.

It said the activities "undercut whatever 'positive contributions' to regional and international peace and security were intended to emerge" from the nuclear agreement.

The statement listed Iranian support for groups including Lebanon's Hezbollah and the Palestinian Hamas movement as well as the Syrian government of President Bashar al-Assad and Houthi rebels in Yemen.

The Trump administration declared yesterday that Iran was complying with the nuclear deal concluded between Iran and six world powers under which Iran agreed to curb its nuclear program in return for sanctions relief.