WASHINGTON — Two weeks after Senate Republicans issued a letter to the Iranian leadership warning that any nuclear agreement Iran signs with the administration may be temporary, President Obama has issued a missive of his own: A video directed at Iran’s young people, urging them to pressure their leaders to accept the deal on the table.

The ostensible reason for the video was a greeting for Nowruz, the Persian New Year celebration that Mr. Obama has used before to deliver messages to the Iranian populace. But after mentioning a celebration held at the White House, he wasted no time making his case that an agreement that freezes Iran’s nuclear program could open the way to a far larger relationship.

He describes such a relationship in terms meant to appeal to a young Iranian population that the White House believes cares little about Iran’s nuclear capability and desperately wants access to the West, its culture and its universities.