The two leaders will be in the Iranian capital during August 26-31 to attend the NAM summit and they are expected to meet on the sidelines, The News daily quoted its sources as saying.
They are expected to discuss recent developments in India-Pakistan relations and in the region.
Zardari and Singh last met in New Delhi in April when the Pakistani President made a private visit to India to pray at a Sufi shrine in Ajmer.
Last week, Zardari formally invited Singh to visit Pakistan in November.
He is expected to remind the Indian leader about his invitation during their likely meeting in Tehran.
Zardari is also expected to meet his Iranian counterpart Mahmoud Ahmadinejad.
The Pakistan President will travel to Iran after visiting Saudi Arabia for a summit of Muslim countries convened by King Abdullah on August 14.
The rotating presidency of NAM will be conferred to Iran on August 26.