"In our opinion, it is too early to assess whether Iran has returned to the negotiating table in Vienna for constructive work," RIA Novosti quoted State Department spokesman Jalina Porter as saying.
Earlier, the foreign ministers of the G7 countries called on Iran to conclude an agreement on the JCPOA.
Russia's Permanent Representative to International Organizations in Vienna Mikhail Ulyanov said that the parties at the talks in the Austrian capital noted a number of important common features in their positions.