U.S. Vice President Joe Biden urges Turkey to increase sanctions against Iran aimed at forcing Tehran to stop its nuclear activities.
Turkey opposed the latest round of UN sanctions against its fellow Muslim neighbour.
The European Union added 180 people and entities to its Iran sanctions list on Thursday and laid out plans for a possible embargo of Iranian oil.
Sanctions have had an impact on Iran's economy but the West suspects they have not stopped work to develop nuclear weapons.
Tehran insists its nuclear activities are peaceful.
Biden said on Thursday he had no evidence the attack on the British embassy in Tehran was orchestrated by Iranian authorities.
But he did say it was another example of why the country was a "pariah."
Lily Grimes, Reuters