TOKYO -- Japanese Prime Minister Shigeru Ishiba on Saturday expressed his strong disappointment that a new 25 percent US tariff on auto parts took effect earlier in the day.

Ishiba told reporters that Japan will continue to ask US President Donald Trump's administration to reconsider its tariff measures.

The US administration on Saturday imposed a new 25 percent tariff on imported auto components, including engines and transmissions, in another blow to Japan's mainstay car industry already slapped with the same rate of tariff on automobiles that took effect in early April.

Ishiba also said Japan is negotiating with the United States on "all" US tariffs, following reports that the US side is unwilling to offer exemptions on duties imposed on products such as auto and steel.

The US administration told Japan in their second round of negotiations, held in Washington on Thursday, that it aims to focus mainly on reciprocal tariffs in its negotiations with Tokyo while not including duties on automobiles, steel and aluminum, Kyodo News reported, citing Japanese government sources.

Japan has no intention of striking a trade deal with the US administration unless all of its new tariffs are reviewed, top negotiator Ryosei Akazawa said Saturday as he returned to Japan from the ministerial-level talks in Washington.

"We have pressed the United States to reconsider the series of tariffs and we can not reach an agreement if that is not properly addressed in a package," Akazawa, who is Japan's economic revitalization minister, told reporters.