Russia's foreign minister said Saturday that relations with the United States are on a positive track under Barack Obama's administration, but warned that Moscow won't make any trade-offs like agreeing to increase pressure on Iran. Sergey Lavrov said Moscow is feeling a "cautious optimism" about relations with Washington. "We are satisfied with how our relations with the new US administration are developing," Lavrov said in a speech to a group of political scholars. "Mutual confidence was being eroded for a long period, and it will take time to rebuild it. But we are moving now in the right direction." Russian-US ties plummeted to their lowest point since the Cold War under George W. Bush's administration amid Moscow's protests over US missile defense plans and other disputes. Obama and Russian President Dmitry Medvedev met in London last week and ordered negotiators into immediate action on a treaty to further reduce nuclear weapons. Russian officials have voiced hope that Obama will dump his predecessor's plan to deploy missile defense sites in Poland and the Czech Republic. Obama has not said how he intends to proceed with the missile shield, but has stressed the system must be cost-effective and proven. Obama said last month he had told Russia that reducing Iran's pursuit of a nuclear weapon would lessen the need for a US-planned missile defense system in Eastern Europe. Medvedev has said that Moscow will cooperate with Washington in dealing with the Iranian nuclear standoff, but ruled out any quid pro quo on missile defense and Iran. Medvedev and Obama said in a joint statement after their meeting in London that Iran needs to restore international confidence in the peaceful nature of its nuclear program - a sign that the Kremlin to some extent shared US concerns that Teheran was trying to build nuclear weapons. Iran says its uranium enrichment program is solely aimed at generating electricity. While saying that Teheran mustn't be allowed to develop atomic weapons, Moscow has been cautious not to anger Iran, an important business partner. Moscow is building Iran's first nuclear power plant, has provided Teheran with weapons and needs Iranian assistance on the Caspian and other regional issues. Lavrov made it clear Saturday that Moscow had no intention of being tougher with Teheran in order to please Washington. "It's our neighbor, it's a country which can play a very important role in solving a number of acute international issues, such as the situation in Afghanistan, Iraq and different aspects of Mideast peace settlement," Lavrov said. "We aren't closing our eyes on remaining questions about the Iranian nuclear program. But it would be unrealistic to expect us to raise pressure on Iran beyond what has been agreed upon." On a more general note, Lavrov warned that Moscow wouldn't engage in any kind of quid pro quo. "Any trade-offs would be unprincipled and unrealistic," he said. "They would undermine trust in our diplomacy, and we cherish that trust no less than others."