Subpoenas were issued a few months ago by investigators from the Department of Justice and Securities and Exchange Committee (SEC) the source told AFP, speaking on condition of anonymity.
The investigators also want to interview a Goldman Sachs employee over the bank's role, according to The Wall Street Journal, which first broke the story.
The US officials, who base their authority on the Foreign Corrupt Practices Act, want to know why Goldman Sachs did not report transactions deemed suspicious that involve funds raised by bond offerings worth USD 6.5 billion (5.8 billion euros) for 1MDB, the source said.
The investment bank is collaborating with US regulators, the source said, and is also providing information to regulators in Singapore, which is also carrying out a probe, The Journal reported.
More From This Section
When contacted by AFP, Goldman Sachs had no comment.
US regulators want to see if Goldman Sachs followed US banking laws that requires banks and financial institutions to report suspicious transactions.
Goldman has rejected any charges linking them to corruption.
Malaysia has been gripped for more than a year by allegations that billions of dollars were looted from state investment fund 1MDB in an audacious campaign of fraud and money laundering.
"The Department of Justice will not allow the American financial system to be used as a conduit for corruption," US Attorney General Loretta Lynch said on announcing the legal action.
Lynch said the funds taken from 1Malaysia Development Berhad had been meant to help develop the Malaysian economy.
"Instead, they were stolen, laundered through American financial institutions and used to enrich a few officials and their associates," she said.
Both Najib and 1MDB have consistently dismissed allegations of wrongdoing as political attacks by his opponents.