South Korea's Acting President Han Duck-soo has said South Korea will not form a coalition with China and Japan to jointly respond to US tariff measures, but seeks to resolve related issues through negotiations with Washington.

Han made the remark in a CNN interview released on Tuesday, a day before the Trump administration's 25 per cent "reciprocal tariff" for South Korea took effect -- a measure that is feared to hit hard the Asian country's export-driven economy.

"I don't think that kind of fighting back will improve the situation dramatically," Han was quoted as saying by the news channel when asked if Seoul would work together with Japan or China to fight the US tariffs.

"We will not take that route," he added.

The interview was released shortly after Han spoke with Trump in the allies' first leader-to-leader phone conversation since Trump took office in January. Han has taken the mantle as acting President as South Korean President Yoon Suk Yeol was impeached over his short-lived martial law imposition in December and removed from office last week.

As Trump has announced duties on what his administration called "worst offenders," including key US allies and partners, some observers have raised the possibility of affected countries banding together with China to fend off Trump's escalating tariff salvo, Yonhap news agency reported.

Trump's tariff pressure has been weighing heavily on Asian economies as he announced a minimum 10 per cent "baseline" tariff and reciprocal tariffs last week following the rollout of 25 per cent tariffs on steel and aluminum imports as well as on imports of foreign vehicles. His administration is also looking to place tariffs on semiconductors, pharmaceuticals and other items.

Trump has been using tariffs to increase federal government revenue, pare down America's trade deficits, draw in foreign investments and boost domestic manufacturing despite concerns that tariffs could lead to higher inflation and slower economic growth.

Denouncing the tariff plans, US Senator Brian Schatz (D-Hawaii) brought up the recent trilateral meeting among the Trade Ministers of South Korea, Japan and China, calling the picture of the three "the most shocking image" that possibly indicates the world is "uniting against" America.

While describing the newly announced levies as "a pity", Han said that South Korea would "negotiate in a cool way" with Washington to work out a solution based on the two countries' "very strong alliance," according to CNN.

Han said that "not everything will be solved in a day or two," expressing optimism that a resolution can be reached.

"I think we should, in a very cool way, assess what this kind of 25 per cent means for us, and we should, in a very cool way, negotiate with them," he was quoted as saying.

Seoul has been making all-out efforts to address the tariff hike, with top trade officials flying to Washington for talks with the Trump administration to address the situation.

In a Facebook post Wednesday, Han reaffirmed Seoul's commitment to working with Washington.

"There are countries that are choosing the hard-line response with retaliatory tariffs, but at difficult times like this, I believe the more sensible solution is to upgrade the South Korea-US alliance to make it stronger as a security alliance and an economic alliance," he wrote.

"The best way to solve a problem is to calmly communicate with the other party and persistently seek a path guaranteeing the interests of both sides."