There are one airlines offering flights to Tehran. The most direct route isn’t necessarily the cheapest – being flexible is key to finding the lowest airfare rates. For example, try searching by month to see the best time of the week to fly. The cheapest date is currently 14 / Jun / 2023.
You can use the filters on your search to see more flights and find cheaper rates – Tehran has more than one airport. So if you don't need to fly into Tehran Imam Khomeini Airport, it's worth checking your other options. The 4621 km flight usually takes about 8 hrs 30 mins.
There are about 23 flights to or via Tehran every week, so you have plenty of options.
If you're planning on going to Tehran during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.