Numb, here is some info for you from the experts...a couple tips...anthuriums like humidity, but not wet growing medium. Overwatering can cause leaves to yellow, and also promote fungal growth and root rot. Hope this link helps.
Yes, to me it looks like a classic case of either over watering or under watering. Another thing to keep in mind is these plants do best in Warm climate. This plant is huge in Floria. Remember: Anthuriums grow best with day temperatures of 78 to 90 F, and night temperatures of 70 to 75 F. Temperatures may also be the problem. I don't see any yellow in the leaves from your picture though and that is usually a huge sign for over watering or the improper temperature. Seems like maybe it needs water?
As you live in Iran and the City of Tehran, I assume you have wide fluctuations of Temp and light, I would imagine you will have cooler night temp and pos very bright daylight from early morning, Naturally like everywhere else there are different ways and means of altering the light / shade inside and also helping our plants in pots to make the best use of heat or cool for our plants.
I can grow these plants INDOORS in conservatory here in Scotland UK with much success, so long as I offer good light but NOT direct sunlight through glass windows, so I would site these plants in bright area but where there is a little shade from sun, so I place these UNDER any larger leaved plants that can take more sunlight, I also water them from the bottom, that is when I stick my finger into the soil and it feels a bit dry, I would sit the plant in a bowl of water and about hour / or 30 min's, the top soil would change colour to a darker brown, that tells me the soil is wet enough, remove from bowl of water and allow the pot to drain before setting down in it's shaded area again, DON'T allow the plant to sit in a saucer of water more than an hour.
I also give the foliage a light misting with tepid (baby bath temp) water. They grow in their natural environment where there is humidity around the plants due to damper lightly shaded conditions.
Dry heat causes the foliage to burn / brown and it wont recover, you have to remove this brown foliage by cutting it off.
Also as stated above, too much water / wet soil over several days caused the foliage to go brown, pos even produce mould or fungus to take hold and will show as grey /black powdery stuff forming on either leaf or stems.
Soon as any flowers have finished/ died, remove them by cutting the stem about inch above the soil, this helps the plant save energy as this saves plant energy by making seeds as you have removed the flower, it also helps the plant produce more flowers as that is what nature tells plants to do (germinate, grow, flower, set seeds and in some cases Die)
I give my Anthurium's a half strength INDOOR liquid plant feed, every 2 weeks at watering time, but stop over the winter months here from about October- March, I also give less water as the plant will want a rest after flowering all summer, also in summer I try to place outside for several hours in hot sunny days but NOT against a wall or in areas where the sun can bake or burn the plant.
Last bit of advice would be, never re-pot into too large a plant pot as, like a lot of similar plants with the same requirements, they flower best when they are in pots where they are over big for the pot size, IF you need to up the pot size, maybe just 2 sizes above the pot it is in, at this time remove any dead or unhealthy root by cutting off with sharp knife, don't just pull and break the damaged roots as this CAN maybe allow disease to get in.
Hope this helps a little, for now, stick your finger into the soil and if wet, leave off watering, if dry, water as I told you by watering from below.
Good luck and best regards.
I must say the soil looks rather wet in your pictures... Anthuriums need regular watering, but they do not like to be wet. Sounds strange, but they are rather like orchids, in that they do not do well sitting in wet soil, but prefer to drain quickly.