US President Donald Trump's tariffs on Japanese goods are a "national crisis", Prime Minister Shigeru Ishiba said Friday ahead of cross-party talks on mitigating the impact on the heavily export-dependent economy, AFP reports.

Japanese firms are the biggest investors into the United States but Trump on Thursday announced a hefty 24 percent levy on imports from the close US ally as part of global "reciprocal" levies.

The measures "can be called a national crisis and the government is doing its best with all parties" to lessen the impact, Ishiba said in parliament.

He called, however, for a "calm-headed" approach to negotiations with Trump, who has also imposed 25 percent tariffs on auto imports which came into force this week.

Local media reported Friday that Japanese officials were attempting to organize a call between Ishiba and Trump, who held apparently friendly talks at the White House in February.

For his part, Japanese Foreign Minister Takeshi Iwaya "strongly demanded" to US Secretary of State Marco Rubio in talks in Brussels on Thursday that the "extremely regrettable" measures be reviewed, Tokyo said.