Venezuela, an OPEC member and home to one of the world's largest oil reserves, assumed the movement's rotating presidency from Iran which had hosted the bloc's summit in 2012.
Iranian President Hassan Rouhani, while opening the 17th meeting of the Non-Aligned Movement (NAM), said the member countries have the opportunity to discuss the concerns and the developments at the bilateral and international level.
The summit is convening at a time when peace is being threatened all across the world, he said. "National sovereignty of developing states is being constantly violated".
Iran was the first to warn of "Takfirism" in Syria, he said.
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NAM countries should not pin their hopes on big powers to achieve development and growth, he asserted.
The "Zionist regime" is trying to exploit the situation in the Middle East, the Iranian President said, adding that Iran supports the cause of the Palestinians.
The summit in Venezuela comes amid anti-government protests in the South American country. A number of people were arrested there earlier this month after President Maduro was greeted by pot-banging demonstrators during a visit to the Margarita island.
The government has deployed over 14,000 security personnel to the region in a bid to contain any unrest near the summit.
Venezuela's political and economic crisis triggered by a
fall in oil prices has left it increasingly isolated, including in its own region.
The turnout of heads of states for the conference has been low this year with Zimbabwe's Robert Mugabe, Iran's Rouhani and Palestine's Mahmoud Abbas among the few heads of states who have landed on this Caribbean island.
Ansari is leading the Indian delegation for the Non-Aligned Movement (NAM) Summit in the absence of Prime Minister Narendra Modi, who is only the second Indian premier not to go for the conference after Charan Singh in 1979.
India is one of the founding members of the Non-Aligned Movement and had hosted the 7th NAM Summit in 1983 in New Delhi.
The membership of NAM comprises 53 countries from Africa, 39 from Asia, 26 from Latin America and the Caribbean and 2 from Europe (Belarus, Azerbaijan). There are 17 countries and 10 international organisations that are observers at NAM.
The Non-Aligned Movement came into being 55 years ago when leaders of 25 developing countries met at the 1961 Belgrade Conference.