Sen. Mark Warner (D-Va.) on Sunday said he fears that the United States doesn't have the "full power of pressure" against Iran.
His comments coincide with the Trump administration's push to dismantle Tehran's nuclear development program after striking three of their facilities last year.
President Trump sent the USS Abraham Lincoln aircraft carrier to the region in late January, escalating tensions and the possibility of future strikes amid indirect talks with Iranian leaders in Oman. The U.S. military also shot down an Iranian drone near the aircraft carrier earlier this month.
"What I fear is that we don't have the ability to bring the full power of pressure against Iran," Warner said of the current circumstances during an appearance on CBS News's "Face the Nation."
"A few weeks back, when the Iranian people were bravely in the streets, and there might've been a moment, we couldn't strike because the aircraft carrier that was usually in the Mediterranean was off the coast of Venezuela during the blockade there," he added, referring to the USS Gerald R. Ford.
Trump sent the USS Gerald Ford to the Latin American region in November with more than 4,000 sailors and dozens of tactical aircraft on board.
The Department of Defense (DOD) directed the departure from the Mediterranean in late October for what officials said was assistance in dismantling transnational criminal organizations and curbing drug-smuggling.
However, Warner said the decision left people in the region defenseless.
"When the Iranian people were out in the street en masse, and the president said, hey, don't worry, we're going to come help you, he couldn't because or chose not to, because we didn't have that our full fleet there because the aircraft carrier that would normally be in the Mediterranean was off the coast of Venezuela being part of that blockade," the Virginia senator said during an appearance on "Fox News Sunday."
"And at that same moment in time, when again, the people in Iran were protesting, the regime is awful, our potential other allies in the region, the Europeans who have relations with Iran, could have been putting enormous pressure on the Iranians, but they were too busy focused on Greenland and preserving NATO," he added.
Trump issued strong statements backing groups of Iranians who were leading anti-government protests last month and promised to provide military intervention if individuals were killed for participating in demonstrations.
Ultimately, no strikes occurred but thousands were killed in the rise up against the Islamic Republic. Following the deadly demonstrations, the president resumed efforts to dismantle the country's nuclear program.
However, Iran's leaders have maintained that they reserve the right to enrich uranium and develop their weapons.
"Why do we insist so much on enrichment and refuse to give it up, even if a war is imposed on us? Because no one has the right to dictate our behavior ... ," Iranian Foreign Minister Abbas Araghchi said on Sunday, according to The Times of Israel.
"They fear our atomic bomb, while we are not looking for one. Our atomic bomb is the power to say 'no' to the great powers," he added.
Still, Warner encouraged the president to keep the pressure on the Iranian regime.
"Clearly, he's got a fleet now off the coast, he's got the military option. I would hope that we could continue to ratchet up pressure from not just our sanctions, but also more of the Europeans as well," he told host Shannon Bream.
"We've got to try to find ways to get rid of that regime, though," he added.