Iran has summoned a Swiss official to protest remarks made by Rex Tillerson.
Last week, the US Secretary of State made clear US policy on Iran - the country plans to "reduce its hegemony" over the Middle East, thereby reducing its nuclear capability and power to influence other elements in the region.
Tillerson said the policies were in place in order to ensure a peaceful change of regime.
The Swiss charge d'affaires was summoned to the Foreign Ministry in Tehran to lodge a protest over this.
The Iranian government claims these remarks go against the United Nations Charter and international rules.
Switzerland, as a country, represents US interests in Iran.