March 31 (Reuters) - Iran complained to the United Nations Security Council on Monday about "reckless and belligerent" remarks by U.S. President Donald Trump, describing them as "a flagrant violation of international law" and the founding United Nations Charter.

Trump threatened Iran on Sunday with bombing and secondary tariffs if Tehran did not come to an agreement with Washington over its nuclear program.

In a letter, seen by Reuters, Iran's U.N. Ambassador Dedicated Private Proxies Cheap Amir Saeid Iravani wrote that Tehran "strongly warns against any military adventurism and will respond swiftly and decisively to any act of aggression or attack by the United States or its proxy, the Israeli regime, against its sovereignty, territorial integrity, or national interests." (Reporting by Michelle Nichols; Editing by Ismail Shakil)