The Summit of the 120-nations grouping will open with Iran assuming the Chair from Egypt for the next three years.
Prime Minister Manmohan Singh is leading the Indian delegation to the two-day Summit which is being attended by over 30 Heads of State/Governments.
While the US has asked countries not to attend the NAM Summit due to its venue, Iran is projecting the presence of world's leaders as a big diplomatic win.
Asked about crucial issues, including Syria on which the members have differing views, government sources said: "We don't expect any fireworks on Syria... the attempt is to have a successful outcome of the Summit."
United Nations chief Ban Ki-moon also arrived in Tehran as an invited observer to the summit. The United States and Israel have criticised his presence in Iran.
Leaders already reported to have arrived in Tehran include Afghan President Hamid Karzai, Bangladesh Prime Minister Sheikh Hasina, Benin President Thomas Boni Yayi, Bhutanese Prime Minister Jigmi Thinley and Cambodian Prime Minister Hun Sen.
Iran is under four rounds of UN Security Council sanctions for turning down West's calls to give up its right of uranium enrichment.
Also, the US and its allies have imposed severe sanctions on Tehran hoping to force it to a negotiating table.