US President Donald Trump on Thursday accused French President Emmanuel Macron of sending "mixed signals" to Iran on behalf of the United States.

"Iran is in serious financial trouble. They want desperately to talk to the US, but are given mixed signals from all of those purporting to represent us, including President Macron of France," Trump tweeted.

"I know Emmanuel means well, as do all others, but nobody speaks for the United States but the United States itself. No one is authorized in any way, shape, or form, to represent us!" he added.

Media reported earlier this week that Macron had invited Iranian President Hassan Rouhani to attend the G7 summit at the end of this month, but a French diplomat denied the report on Wednesday.

France and other US's European allies have been attempting to save the Iran Nuclear Deal, which the Trump administration abandoned last year.

Ties between the United States and Iran have deteriorated significantly in recent months due to repeated US sanctions as well as military frictions between the two countries.