On May 27, the same day Iranian president Hassan Rouhani had a telephone conversation with Russian president Vladimir Putin, Iran's foreign ministry denied a report by a Kuwaiti newspaper that the U.S. has sent a threatening message via Russia to Iran.

The Al Rai newspaper in Kuwait had reported that the Trump administration sent a message saying that if Iran harmed American troops in Syria or Iraq, the U.S. would attack military bases inside Iran.

According to Al Rai's report, the message was sent via Russian military officers who were in contact with their American counterparts.

Russia and Iran are allies in the Syrian conflict in defending the country's strongman, Bashar Al Assad. The U.S. supports some anti-Assad groups.

On May 18, American warplanes attacked a pro-Assad military column that was approaching U.S. supported opposition forces in an area agreed upon as a no-fighting zone by all parties involved.

A week later, two U.S. lawmakers sent a letter to secretary of state Rex Tillerson and defense secretary James Mattis asking them not to allow Iran to establish a permanent presence in Syria.

Israeli officials have also recently voiced concern about Iran's presence in Syria and near Israeli borders.

Nevertheless, in his telephone conversation with Putin on Saturday, Rouhani underscored Iran's intention to continue its cooperation with Russia and Syria.

According to the official website of Iran's president, Putin in turn told Rouhani that his re-election speaks of popular backing by the Iranian people for the Islamic Republic's domestic, regional and foreign police.