Both developments showed the difficulty faced by governments like Russia, France, and India which have vowed that they will maintain their business ties with Tehran despite a US decision to withdraw from Iran's nuclear deal with world powers and reimpose sanctions.
Her comments came hours before a meeting with Iranian Foreign Minister Mohammad Javad Zarif who is here to seek India's support to salvage the nuclear deal.
The issue is expected to be discussed extensively in the talks between Swaraj and Zarif, officials said. Swaraj said "all parties to the agreement should engage constructively for peaceful resolution of the issues", according to a foreign ministry statement.
Trump also said he would reinstate United States nuclear sanctions on Iran suspended under the nuclear accord and impose "the highest level" of economic bans on the Islamic Republic.
Both countries are key oil suppliers to India and the United States has warned that foreign companies which deal with Iran could themselves be punished. India and Iran already have an Indian Rupee (IR) mechanism which has worked well during the previous sanctions era.
According to media reports, India may resume payments to Iran in rupees - to shield exporters from the USA sanctions.
On Prime Minister Modi holding informal summits with China and Russian Federation, she said, informal summits are new dialogue mechanism by India to strengthen and further deepen bilateral relations. They have said that, as long as Iran is able to continuing selling its oil around the world, Tehran will honor the nuclear deal.
Sushma Swaraj said India has interacted at the Ministerial level with 186 out of 192 countries in the world.
India and the USA have been increasing defence co-operation and Predator Drones are one of the most eagerly anticipated acquisitions - especially because of its use in anti-terror operations.
"Jab seema par janaze uth rahe hon, to baatcheet ki awaaz acchi nahi lagti (when there are funeral processions taking place on the border, talk of dialogue is not appropriate)", Swaraj said. An unhappy Mr Modi also told his British counterpart that whenever Indian fugitives take shelter in Britain, it takes a lot of time to extradite them to India.