Iranian nuclear negotiators met with permanent U.N. Security Council members and Germany this week, following similar meetings early this year in Turkey and Iraq.
Iran is suspected of using a civilian nuclear program as cover for a weapons program. Tehran, however, maintains its right to pursue nuclear technology under the terms of international protocols.
British Foreign Minister William Hague described the talks in Moscow as "detailed" but said significant differences remain. Iran, he said, wasn't serious about discussing its uranium enrichment activity.
"This is a missed opportunity to address the serious concerns of the international community," he said.
Hague said there were no plans for another round of talks with the Iranians.
"However nuclear experts from both sides will meet to offer further clarity on technical issues, following which we will consider whether there is sufficient basis for further political talks," he said in a statement.
Saeed Jalili, Iran's chief nuclear negotiator, was quoted by state-funded broadcaster Press TV as saying Tehran wouldn't negotiate away its basic rights.
"We explicitly announced (in Moscow) that enrichment is Iran's absolute right and that enriching uranium for peaceful purposes is regarded as an absolute right," he said.