Trump in May pulled the U.S. out of the 2015 nuclear accord, saying it had "failed to achieve the fundamental objective of blocking all paths to an Iranian nuclear bomb" and did not deal with Tehran's "malign activities, including its ballistic missile programme and its support for terrorism".
Saudi Arabia, meanwhile, is set to deliver extra 4 million barrels of its oil to India in November, in what could be a Saudi move to replace lost Iranian barrels.
A top United States envoy on Iran is headed to India this week for talks ahead of the November 4 deadline set by the Donald Trump administration for countries to bring down their import of Iranian oil to zero.
"We make our policies very clear to those countries".
Japanese officials have said Iran's oil is "extremely important" to their country's energy security.
On November 4, a second batch of potentially more damaging sanctions will be re-imposed on Iran's oil and shipping sectors as well as its central bank.
The Trump administration has given the same message to all countries around the world, and the President has said that the United States is committed to re-enforcing all of its sanctions. "The President had addressed it - I believe it was just earlier today - which he was asked about that question about whether or not India would buy oil from Iran after sanctions are reimposed".
Special representative on Iran Brian Hook, accompanied by assistant secretary of state for energy Francis Fannon, will meet "Indian government counterparts for consultations", the state department announced Thursday. "And the President said - and I'm not going to get ahead of the President, certainly - but he said we'll take care of that", she said.
Of the 220.4 million metric tonnes (million MT) of crude oil imported by India in 2017-18, about 9.4 per cent, was from Iran.
On the implication of the Countering America's Adversaries Through Sanctions Act or CAATSA on India after it inked the Dollars 5 billion deal with Russian Federation to purchase the S-400 Triumf air defence system, Ms Nauert said, "He (the president) was asked also about CAATSA sanctions and possible imposition of CAATSA sanctions".
While Trump's comments did not reveal much despite their ominous portent, Nauert added a new edge to them even saying, "But certainly when we hear about things such as purchasing oil or purchasing of the S-400 systems, it's not helpful.The United States Government just reviews that very carefully".