“The leaders of Iran must recognize that now is the time for a diplomatic solution, because a coalition stands united in demanding that they meet their obligations, and we will do what is necessary to prevent them from getting a nuclear weapon,” said the President in his State of the Union address on Tuesday.
The brief sentence in the hour-long speech was fairly consistent with Obama’s remarks on Iran from previous addresses, but  may offer clues in its emphasis on a “diplomatic solution.”
In his 2010 and 2011’s speeches–years that the White House focused largely on ramping up pressure on Iran–Obama focused his remarks on how diplomacy had been utilized to isolate Iran, and ramp up tougher sanctions.
In 2010 he said:

These diplomatic efforts have also strengthened our hand in dealing with those nations that insist on violating international agreements in pursuit of these weapons. … That is why the international community is more united, and the Islamic Republic of Iran is more isolated. And as Iran’s leaders continue to ignore their obligations, there should be no doubt: they, too, will face growing consequences.

In 2011:

Because of a diplomatic effort to insist that Iran meet its obligations, the Iranian government now faces tougher sanctions, tighter sanctions than ever before.

In 2012, with serious concerns of a looming military confrontation and pressure on the President to draw a “red line,” Obama stated clearly that prevention was his policy but peaceful options remained:

And we will safeguard America’s own security against those who threaten our citizens, our friends, and our interests. Look at Iran. Through the power of our diplomacy, a world that was once divided about how to deal with Iran’s nuclear program now stands as one. The regime is more isolated than ever before. Its leaders are faced with crippling sanctions. And as long as they shirk their responsibilities, this pressure will not relent. Let there be no doubt: America is determined to prevent Iran from getting a nuclear weapon, and I will take no options off the table to achieve that goal.
But a peaceful resolution of this issue is still possible, and far better. And if Iran changes course and meets its obligations, it can rejoin the community of nations.
The renewal of American leadership can be felt across the globe. Our oldest alliances in Europe and Asia are stronger than ever. Our ties to the Americas are deeper. Our iron-clad commitment — and I mean iron-clad — to Israel’s security has meant the closest military cooperation between our two countries in history.

Whether or not this year’s comments suggest the White House is looking to invest political capital in negotiations that promise few quick fixes and may ultimately require a showdown with Congress over sanctions flexibility remains to be seen. The U.S. and P5+1 will enter a new round of negotiations with Iran on February 26 in Kazakhstan.