Russia's foreign minister described U.S. unilateral sanctions on Tehran as "unacceptable in principle" especially if used for self-serving purposes.

Russia has backed Iran's right to develop its weapons capabilities while denouncing Washington's new batch of unilateral of sanctions as “unacceptable and irresponsible.”

Moscow also said the measures go against the spirit of the P5+1 nuclear deal, or Joint Comprehensive Plan of Action, JCPOA.

"The missile program budget is basically Iran’s business. It is not prohibited from having this program," Russian Foreign Minister Sergei Lavrov told reporters at a joint news conference with his Bolivian counterpart, Fernando Huanacuni Mamani. "There are no legal bans in UN Security Council resolutions on this issue."

Lavrov also warned Washington against upsetting the deal, which was agreed after more than a year of painstaking negotiations in July 2015 by Iran, the European Union, Germany, and the five permanent members of the United Nations Security Council — Russia, the United States, China, France, United Kingdom.

Since then, the U.S. has imposed various restrictions on Iran over its missile program, the most recent were announced on July 28.

"Unilateral sanctions are unacceptable in principle and irresponsible if they are used to change in one’s favor a well-calibrated balance (as is the case with the Iran nuclear deal) because they may upset this balance,” Lavrov said. “One shouldn't resort to such provocations because the matter deals not even with national interests of a country but with an enormous region where we are interested in ensuring a nuclear-free status.”

"One should not come up with such provocations, since the issue at hand is the interests of a vast region where we would like to secure a non-nuclear status rather than some individual country’s national interests," he added.

The warning comes after Iran's president, Hassan Rouhani, stated that any continuation of Washington's hostile attitude would result in Tehran scrapping the deal and returning its nuclear program to a pre-JCPOA operational level.

Expressing his hope that Tehran abstains from such a move, Lavrov added that the White House's adherence to its commitments remain equally important.