The United States has tightened Iran's temporary oil export waiver by imposing fresh sanctions and shortening the relief period, triggering a sharp reaction from Tehran and raising concerns over renewed tensions.

Iran's Foreign Ministry strongly condemned the US decision, calling it a violation of the memorandum of understanding reached between the two countries. The ministry said Washington had unilaterally changed the agreed terms, putting recent diplomatic progress at risk.

In an official statement, Iran said it would take all necessary measures to safeguard its national security and economic interests. Tehran also warned that it would respond appropriately to the latest US action.

According to Iranian officials, responsibility for the current situation rests entirely with the United States, which they say has backed away from commitments made under the bilateral understanding.

Following the memorandum of understanding, Washington had allowed Iran to continue limited oil exports until August 21. However, the US Treasury Department has now reduced the waiver period, allowing the exemption to remain in effect only until July 17.

US officials said the decision was taken in response to recent attacks in the Strait of Hormuz and the deteriorating security environment in the region. Washington maintains that the new sanctions are aimed at addressing growing regional security threats.

Iran has rejected that justification, arguing that increasing economic pressure through sanctions will only fuel instability and deepen tensions across the Middle East.

Analysts believe the latest move could further strain diplomatic relations between Tehran and Washington, while global energy markets are closely monitoring the situation for any impact on oil supplies and prices.