"As regards Iran nuclear program talks, I remain cautiously optimistic," Lavrov told reporters at UN headquarters in New York.
Negotiators from Britain, China, France, Russia, the United States plus Germany began a new round of talks last Friday with only two months before a new November 24 deadline to reach a deal on Tehran's suspect nuclear program.
"If we look at the drafting process of the text, we are very close to our goal but there are sections remaining. These sections are the most complicated," Lavrov said.
"I have this feeling that all parties are interested in seeing a productive resolution. We still have time until November 24," he said.
"We'll do our utmost to make sure that the remaining small, but extremely important issues be resolved in a way that would be acceptable to all," he added.