TEHRAN — The French carmaker Renault signed a multimillion-dollar deal in Tehran on Monday, agreeing to raise vehicle production in Iran just days after President Trump signed into law new sanctions against the country.

The roughly $780 million agreement to produce as many as 150,000 additional cars a year is the largest foreign auto deal in Iran’s history, state-run PressTV said. It was a victory for President Hassan Rouhani, who was sworn into office on Saturday after being re-elected this year promising to revitalize an economy hurt by sanctions.

Iran, an Islamic republic, is increasingly attracting foreign investors, despite restrictions imposed by the United States over its missile program and its military activities in the region.

Its economy has limped along, surviving mainly on oil sales in recent years, with youth unemployment topping 40 percent and the state controlling many sectors. American restrictions stop most international banks from providing financing or credit to Iran, and the country is cut off from international payments systems for using debit and credit cards.