South Korea's president, Lee Jae Myung, has ruled out sending troops to the Middle East in any capacity that could draw the country into the ongoing conflict in Iran, pushing back against pressure from US President Donald Trump.

"There won't be deployment that would involve or enter war. I can tell you that very clearly," Lee said at a news conference on Friday. "We won't deploy military assets in any form to that end."

Lee did, however, indicate he was reviewing whether South Korea should take a greater role in protecting navigation in the region. South Korea currently maintains a naval presence off the coast of Somalia as part of an anti-piracy mission.

"[It] is also clear that we must do the minimum as other countries do to protect our commercial shipping and crude shipments, and also the safety of our people," he said.

Trump has criticised Seoul for what he described as insufficient support for the Iran war. This summer, Washington scaled back major joint military exercises between the two countries, a move that unsettled the US ally.

South Korea's government has been reviewing a possible military deployment to the Strait of Hormuz, though the idea has proven unpopular domestically.

On trade, Lee said the two sides were nearing an agreement but that certain elements remained difficult for Seoul to accept. He identified concerns over the commercial viability of the package as the main sticking point.

South Korea committed last year to invest $350 billion in US manufacturing in exchange for Washington lowering tariffs on Korean imports to 15%. Seoul this week postponed a parliamentary briefing on the investment plans, which is now expected to take place next week.

Lee also addressed the prospect of a meeting between Trump and North Korean leader Kim Jong-un, saying such a meeting was possible in the coming months but that many factors would need to align.

"What's clear is that President Trump wants talks, and I want him to as well, and we're continuing coordination to make dialogue between the North and the US possible," Lee said.

North Korean state media has so far remained largely silent on Trump's repeated calls for such a meeting. According to reports, Trump has been pushing aides to arrange a meeting with Kim as soon as this autumn.