Iran opened a channel to a "moderate" opposition group about a month ago, The Daily Telegraph quoted several opposition sources as saying on Monday.
Officials met Haytham Manna and other members of a group known as the National Coordinating Body for Democratic Change, or the National Coordinating Committee.
The group is strongly opposed to foreign intervention in Syria, and is likely to be seen as more acceptable to Iran than the largest group, the Syrian National Council, which has argued for "international protection" for civilians.
"Iran used Haytham Manna to prepare for an opposition conference," one opposition journalist said. But he said the attempt failed as "no one trusted Iran".