Short answer: Yes — 4G LTE is widely available in Iran, especially in cities, most towns and on many major roads. The three main mobile operators (MTN Irancell, MCI / Hamrah‑e Aval and RighTel) operate commercial 4G/LTE networks; networks were rolled out from the mid‑2010s and coverage has expanded since then. (brandradar.org)

What to expect in practice

• Cities (Tehran, Mashhad, Isfahan, Shiraz, Tabriz, etc.): good 4G/LTE availability and typical smartphone speeds. (brandradar.org)
• Smaller towns and many highways: 4G is common but quality and speeds vary by operator and location. (nperf.com)
• Rural, mountainous or remote areas: coverage drops to 3G/2G or may be absent. (Medialandscapes.org)
• Occasional national or regional internet shutdowns, blocks or throttling can make access unreliable during political crises — this is a separate risk from physical LTE coverage. (en.wikipedia.org)

Practical notes

• If you travel there, a local SIM from Irancell or MCI typically gives the best 4G experience; prepay data packages are inexpensive. (irun2iran.com)
• Coverage and speeds are testable with apps/sites such as nPerf and operator coverage maps before you rely on service in a specific area. (nperf.com)

If you want, I can:

• Check coverage maps for a specific city or road in Iran, or
• Compare prepaid data plans from the main operators.