It might seem odd for both Washington and Tehran to use the holiday for political purposes, but there's a certain logic to it. It makes political sense, perhaps, for a U.S. president to jump on a non-Islamic aspect of Iranian culture -- Nowruz predates the state's religion -- as the right moment to send a message to Iranians.
As for Iran's own leadership, both the supreme leader and the president have been putting out political Nowruz addresses for years. The practice of naming years in the address sets a political agenda. Khamenei dubbed this -- 1392 -- the year of "political and economic epic," and past years have been named "domestic production" and "economic jihad." The Islamic Republic and its political institutions are not very old, dating back to only 1979.
Something that's not always evident to outsiders is how much politics is part of life here in Iran. Some, especially Americans, might be under the misperception that Iran doesn't really have politics, that it's all about state mandates. But, in fact, everything here is politicized.
When the national leaders make their annual Nowruz speeches, a huge number of Iranians tune in, regardless of their political tendencies. Whether people are waiting for a sign about the nuclear negotiations or some talk about the election, they're well aware that the positions these two men take could have major implications for their economic well-being, which is still just about every Iranian's top concern at the moment.