"Our concerns about the government of Iran are very well known. Given its current unwillingness to address its international obligations and international concerns about its nuclear programme, we don't think that this is the time for such transactions to be taking place with Iran," assistant secretary of state for south and central Asia, Robert Blake, said.
He was referring to the $7.5 billion gas pipeline deal signed last month between Pakistan and Iran, a project in which India has shown renewed interest.
India's petroleum ministry says that a decision on joining the Iran-Pakistan gas pipeline should not be governed by politics, although talks have hit roadblocks on issues ranging from pricing of gas to security of the pipeline.
"The Iran-Pakistan-India pipeline discussions have been going on," said Petroleum Secretary S Sundareshan, who was accompanying Petroleum Minister Murli Deora during his stay in New York after returning from the International Energy Forum in Cancun.
"We must leave the politics aside, ultimately this pipeline project can progress if the gas is variable at reasonable rates at the India-Pakistan border," he said.
"It's basically going to be a business decision at the end of the day."
In his remarks, Blake said the Obama Administration, which is aggressively working with its international partners at the UN Security Council to slap additional sanctions against Iran, is opposed to the gas pipeline deal inked between Pakistan and Tehran.
"This is a very sensitive time in negotiations with Iran, and we would prefer that all countries not conduct such transactions with Iran at this time," Blake told reporters at the Foreign Press Centre in Washington on Thursday, adding that the US has encouraged Pakistan to try to seek alternatives.