TEHRAN, Iran – Defying week-old U.N. sanctions over its nuclear program, Iran promised to expand its atomic research Wednesday as its president vowed to punish the West and force it to “sit at the negotiating table like a polite child” before agreeing to further talks.

Tehran, which insists its nuclear work is peaceful, said it will build four new reactors for atomic medical research. The U.S. and some of its allies believe Iran is trying to develop nuclear weapons, and the Islamic Republic’s plans to expand research could encourage calls in the West for more economic pressure against the country.

President Mahmoud Ahmadinejad said Iran will not make “one iota of concessions.” He said he will announce new conditions for talks with the West, but first he wants to punish world powers for imposing sanctions.

“You showed bad temper, reneged on your promise and again resorted to devilish manners,” he said of those powers. “We set conditions (for talks) so that, God willing, you’ll be punished a bit and sit at the negotiating table like a polite child,” he told a crowd during a visit to the central Iranian town of Shahr-e-Kord. His speech was broadcast live on state TV.

The Obama administration took its first step in implementing new sanctions Wednesday, leveling penalties against additional individuals and institutions it says are helping Iran develop its nuclear and missile programs and evade sanctions.

The list includes a bank; 22 petroleum, energy and insurance companies; two individuals and four organizations that are part of Iran’s Revolutionary Guard Corps; and five front companies and more than 90 ships that Iran’s national maritime carrier has been using to try to evade sanctions. Some are based in Iran, while others are based in countries including Britain, Singapore, the United Arab Emirates and Germany.

“In the coming weeks we will continue to increase the financial pressure on Iran,” Treasury Secretary Timothy Geithner said. “We will continue to target Iran’s support for terrorist organizations.”

Geithner said at a White House news conference that the administration expects other countries to announce new penalties of their own against Iran soon.

The European Union is expected to announce additional steps today. EU ministers agreed this week to consider tighter sanctions for Iran’s refusal to halt uranium enrichment.

U.S. lawmakers also could press for additional embargoes after last week’s U.N. Security Council sanctions — which were backed by Iranian allies Russia and China.

Iran has rebuffed a United Nations-drafted plan to suspend uranium enrichment and swap its stockpiles of low-enriched uranium for fuel rods. An alternative plan backed by Turkey and Brazil includes the uranium-for-rods exchange, but does not mandate a halt to Iran’s ability to make its own nuclear fuel.