Their comments came after President George W. Bush vowed in a prime-time address to Americans to go after Iranian terrorist networks feeding the insurgency in Iraq.
The US and Iran have been involved in a bitter standoff over Tehran's nuclear program, a clash that has intensified because the United States says Iran helped provide roadside bombs that have killed American troops in Iraq.
Tensions inched upward another notch this week after five Iranians were detained by US-led forces after a raid on an Iranian government liaison office in northern Iraq. Bush's remarks Wednesday in a speech announcing his plan to boost US forces in Iraq, prompted questions from members of Congress about whether the US is considering attacks on Iranian territory.
Bush administration officials have long refused to rule out any options against Iran but said military action would be a last resort.
On Friday, Defense Secretary Robert Gates and Gen. Peter Pace, chairman of the Joint Chiefs of Staff, told the Senate Armed Services Committee that while US forces are trying to prevent Iran and Syria from disrupting US forces in Iraq, there were no immediate plans for an attack.
"We believe that we can interrupt these networks that are providing support through actions inside the territory of Iraq, that there is no need to attack targets in Iran itself," Gates told the panel, adding that he continues to believe that "any kind of military action inside Iran itself, that would be a very last resort."
Pace said special operations forces are continually battling insurgents who are getting aid from Iran. "I think one of the reasons you keep hearing about Iran is because we keep finding their stuff in Iraq," Pace said.
Snow: War plan suggestion an urban legend
Democratic Sen. Joseph Biden, chairman of the Foreign Relations Committee, wrote to Bush on Thursday asking for clarifications on the administration's stance toward attacking Iran. Republican Sen. John Warner and Democrat Robert Byrd raised the issue at a hearing Friday.
"The president seems to have placed diplomacy on the back-burner again," Byrd said.
In his speech Wednesday, Bush chastised Iran and Syria for not blocking terrorists at their borders with Iraq. He specifically blamed Iran for providing material support for attacks on American troops.
"We will disrupt the attacks on our forces," Bush said. "We will interrupt the flow of support from Iran and Syria. And we will seek out and destroy the networks providing advanced weaponry and training to our enemies in Iraq."
On Friday, White House spokesman Tony Snow called the suggestion that war plans were under way an "urban legend."
"What the president was talking about is defending American forces within Iraq, and also doing what we can to disrupt networks that might be trying to convey weapons or fighters into battle theaters within Iraq to kill Americans and Iraqis," Snow said.