Iranian Supreme Leader Ayatollah Seyyed Ali Khamenei said Wednesday that Tehran is not pursuing nuclear weapons.

Khamenei's remarks came after the latest round of talks between Iran and the International Atomic Energy Agency (IAEA) wrapped up late Tuesday evening in Tehran, a second visit by IAEA delegates to the Islamic republic in less than a month aiming to solve the substantive issues over Iran's controversial nuclear program.

Iran is after breaking "the authority of powers that are relying on their nuclear arms," Khamenei said Wednesday, quoted by the official IRNA news agency, when meeting with a group of Iranian nuclear scientists.

He said assassinations and pressures only indicate the " weakness" of Iran's "enemies."

Iranian officials and the IAEA experts held closed-door meetings on Monday and Tuesday but failed to reach any agreement.

The IAEA director Yukiya Amano said Wednesday that no agreement was reached with Iran over its nuclear issue during the recent visit of the agency's team to Tehran.

Amano made the remarks while the senior IAEA expert team, headed by chief inspector Herman Nackaerts, was returning from Iran after the new round of talks. The meeting followed previous talks held in late January, which Iranian media and officials termed "positive and constructive."

"Intensive efforts were made to reach an agreement on a document facilitating the clarification of unresolved issues in connection with Iran' s nuclear program, particularly those relating to possible military dimensions," Amano said in an statement early Wednesday.

"Unfortunately, agreement was not reached on this document," he added.

"During both the first and second meetings, the agency team requested access to the military site at Parchin, but Iran did not grant the permission," according to the statement.

Amano called Iran's refusal to permit the visit to Parchin as " disappointing."

The agency believes Parchin is where Iran's suspicious nuclear activities are carried out.

However, Iranian Foreign Ministry spokesman Ramin Mehmanparast said Tuesday that the IAEA experts' visit to Tehran was for talks with Iranian officials, not for visiting the country's nuclear sites, as Tehran claimed in the previous talks, contradicting the IAEA's remarks.

Based on an IAEA report released in November 2011, the board of the UN nuclear watchdog adopted a resolution on Iran's nuclear program, calling for intensified dialogue between the agency and Iran to find solutions to outstanding issues.

The IAEA report, which alleged that Iran had engaged in nuclear bomb-related activities, was rejected by Tehran, which called the report "imbalanced, nonprofessional and politically-motivated."

Since the report was issued, Western countries have been tightening sanctions on Tehran, causing a free fall of Iranian currency rial's value against the U.S. dollar, which many Iranian businesses and manufacturers need for importing materials for production, and in return inflation soared.