Obama urges Dmitry Medvedev and Hu Jintao to support US pressure on Iran (VIDEO)

President Barack Obama has urged Dmitry Medvedev of Russia and Hu Jintao of China to support US efforts to pressure Iran to stop its sensitive nuclear activities, but failed to win endorsement from either man.

Obama met separately on Saturday with both presidents on the sidelines of a Pacific Rim economic summit in in Honolulu, Hawaii, The Associated Press reports.

Russia and China — veto-wielding members of the U.N. Security Council — remain a roadblock in the US push to tighten international sanctions on Iran.

However, after meeting with Medvedev, Obama said he and the Russian president reaffirmed their intention to shape a "common response" to Iranian nuclear activities, VOA reports, adding that: "Before talking with Hu, the U.S. president said he and the Chinese leader want to ensure that Iran abides by 'international rules and norms.'"

NPR interpreted Obama's comments as being "broad enough to portray a united front without yielding any clear indication of progress."

Medvedev, for his part, was largely silent on Iran during his remarks, merely acknowledging that the subject was discussed. Hu did not mention Iran at all.

A U.N. nuclear agency report released Tuesday that found "credible" evidence existed of Iranian efforts to design an advanced nuclear weapon.

Iran responded to the report by accusing the International Atomic Energy Agency (IAEA) for siding with what President Mahmoud Ahmadinejad called "absurd" US accusations that its atomic ambitions were not peaceful.

(GlobalPost reports: Iran will not retreat from nuclear program, says Ahmadinejad)

Western powers, meantime, have warned that Iran faces more sanctions if it fails to address their concerns.

Obama, who has tried to increase pressure on Iran through the U.N. and unilateral U.S. sanctions, has hinted that military action is an option.

Republican presidential hopefuls, who have sharply criticized Obama's approach to Iran's nuclear ambitions as too weak, disagreed during a campaign debate on whether the US would be justified in a pre-emptive military strike, the AP reports.

Mitt Romney and Newt Gingrich said in Spartanburg, South Carolina, on Saturday that they "would be willing to go to war to keep Iran from attaining nuclear weapons if all other strategies failed," CBS News reported.

However, Ron Paul strongly disagreed, stressing the need to go to Congress before taking military action, while Herman Cain also seemed opposed to an attack, saying the U.S. should "increase sanctions, deploy ballistic missile warships in the region and assist the opposition movement."