French Foreign Minister Jean-Yves Le Drian was in Tehran on Monday to push for pledges on Iran's ballistic missile programme in a bid to preserve the country's historic nuclear deal.
It is the first visit by one of the European signatories to the 2015 nuclear agreement since US President Donald Trump set an ultimatum that he would abandon it in May if it was not "improved."
Le Drian arrived early on Monday in Tehran and held talks with officials including Iran's Foreign Minister Mohammad Javad Zarif.
He was due later to meet President Hassan Rouhani.
Tensions were already surfacing ahead of the talks, with Zarif accusing the Europeans of pandering to Washington.
"In order to keep the US in the Iran nuclear deal, European countries are suffering from extremism and this will ultimately undermine Europe's policy," Zarif told reformist newspaper Etemad.
Trump in January set a 120-day deadline for US lawmakers and European allies to "fix" his predecessor Barack Obama's major foreign policy achievement or face a US exit.
He is concerned that parts of the deal start to expire from 2026 and that it fails to address Iran's missile programme and its regional activities.
A US exit could kill the nuclear deal, which the Islamic republic has refused to re-negotiate.
European countries have voiced increasing concern over the missile programme, which Iran says is purely defensive and not up for negotiation.
Le Drian said last month that the missile programme and Iran's involvement in regional conflicts needed to be addressed if Tehran "wants to return to the family of nations."
'Trump's Parisian lackey'
Iran has insisted it is abiding by the deal, which saw Tehran curb its nuclear programme in exchange for the lifting of crippling international sanctions.
Western powers say the deal prevents Iran from developing nuclear weapons, though Tehran has always said its atomic programme is for peaceful purposes only.
In an interview ahead of the visit, Le Drian told newspaper Journal du Dimanche that Tehran was "exposing itself to new sanctions" if it did not rein in its missile programme.
Conservative media in Iran hit back on Monday, with the daily Kayhan writing: "French foreign minister insults people of Iran before visit to Tehran". Daily Javan headlined its story: "Trump's Parisian lackey in Tehran."
Ahead of the visit, Le Drian's team said that the minister had made it clear to Tehran that he is no "emissary of Donald Trump."
"We want to preserve the nuclear deal because it is working, it's robust and because the Iranians are respecting it," Le Drian's team said.
War in Syria
Le Drian also met Ali Shamkhani, secretary of the Supreme National Security Council and a close ally of Iran's supreme leader Ali Khamenei.
After his talks, he was due to inaugurate a new exhibition with works from the Louvre Museum in Tehran.
Le Drian will also be pushing in his talks to have Tehran put pressure on the Syrian regime, a key ally, to end its devastating assault on the rebel enclave of eastern Ghouta near Damascus.
Despite their differences, Iran has welcomed French efforts to re-engage economically and politically.
Last year, Iran signed a $5 billion gas exploration deal with French energy giant Total, Tehran's biggest since the nuclear accord.