President-elect Donald Trump's administration will focus more on Iran, a top potential security official said on Tuesday, and will aim to render the Islamic Republic less financially capable of aiding Russia and US adversaries in the Middle East.

"The change you're going to see is more focus on Iran," Mike Waltz, Trump's nominee to be US national security advisor, told CNBC in an interview.

"Maximum pressure, not only will it help stability in the Middle East, but it'll help stability in the Russia-Ukraine theater as well, as Iran provides ballistic missiles and literally thousands and thousands of drones that are going into that theater," he added.

The Republican congressman from Florida shares a strong pro-Israel and anti-Tehran stance with many of the incoming president's other top foreign policy picks.

In his last term, President Trump withdrew the United States from an international deal over Iran's disputed nuclear program and reimposed what his administration called a maximum pressure campaign against the Islamic Republic.

By ordering the assassination of a top Iranian military commander, Qassem Soleimani in Baghdad in 2020, Trump earned the lasting enmity of Iran's ruling military and clerical establishment which has repeatedly vowed revenge.

US investigators have alleged that the Islamic Revolutionary Guard Corps sought to enlist an Afghan national to assassinate Trump before the US election, in charges Iran denies.

The reimposition of harsh sanctions enforcement which had eased somewhat under President Joe Biden may herald a new era of confrontation between the United States in Iran as conflict between US ally Israel and armed Iranian fighters rages on.

Waltz said Iran was an obstacle to peace in the Middle East and that oil sales to China were a key lifeline that needs to be cut off.

"As long as they are flushed with cash, the Middle East is just never going to have peace. Iran doesn't want the Middle East to be in peace," he said.

"China buys 90% of Iran's illicit oil, in roughly 2017, 2018, they were exporting 4 million barrels per day. By the end of Trump's first administration, it was down to around 300,000 to 400,000," he added. "So I think we'll be having some conversations with China about their purchases."