WASHINGTON - US President Donald Trump on Friday spoke over phone with Japanese Prime Minister Shinzo Abe on Iran and bilateral trade.

The two leaders discussed Abe's recent trip to Iran, the ongoing US-Japan bilateral trade negotiations and Trump's upcoming trip to the Group of 20 (G20) Osaka summit in late June, the White House said in a statement.

"President Trump thanked Abe for his effort to facilitate communication with Iran," said the statement.

Abe paid a visit to Iran earlier this week, which was the first visit made by a Japanese prime minister since Takeo Fukuda in 1978.

The rare visit aimed at easing tensions between Washington and Tehran.

Iran's supreme leader Ayatollah Ali Khamenei, however, told Abe on Thursday that it was meaningless to exchange message with Trump, according to Iranian state media.

"While I very much appreciate PM Abe going to Iran to meet with Ayatollah Ali Khamenei, I personally feel that it is too soon to even think about making a deal. They are not ready, and neither are we!" Trump tweeted on Thursday.

Abe's visit was also overshadowed by the attacks on two oil tankers in the Sea of Oman on Thursday, with at least one of them operated by a Japanese company.

The Trump administration has claimed that Iran is responsible for the attacks, while Tehran called US allegation as "sabotage diplomacy."