President Obama held his first Rose Garden press conference today, a "two-and-two" with the president of South Korea. As expected, most questions focused on tensions with North Korea. But as the president prepared to leave, reporters shouted after him to discuss Iran.

At first, he joked that he had just spoke about it "seven or eight hours ago." But perhaps aware of high-profile calls for the president to make a stronger statement of support for those protesting what many believe is a flawed outcome, Obama explained his caution at saying more.

"It's not productive, given the history of U.S.-Iranian relations, to be seen as meddling -- the U.S. president meddling in Iranian elections," he said. "What I will repeat and what I said yesterday is that when I see violence directed at peaceful protesters, when I see peaceful dissent being suppressed, wherever that takes place, it is of concern to me and it is of concern to the American people."

He added that he hopes the Iranian government will take "the right steps" to allow demonstrators to continue expressing their views, and again praised what he sees as a growing push for openness there.

"I do believe that something has happened in Iran where there is a questioning of the kinds of antagonistic postures toward the international community," he said. "How that plays out over the next several days and several weeks is something ultimately for the Iranian people to decide. But I stand strongly with the universal principle that people's voices should be heard and not suppressed."

On the issue of North Korea, Obama explained the rationale for new, tougher sanctions.

"There has been a pattern in the past where North Korea behaves in a belligerent fashion, and if it waits long enough is then rewarded," he said. "The message we're sending - and when I say we, not simply the United States and Republic of Korea, but I think the international community - is we are going to break that pattern."

The goal is to welcome North Korea back to the international community, he said. "But belligerent provocative behavior that threatens neighbors will be met with significant, serious enforcement of sanctions that are in place."