Deputy Secretary of State Richard Armitage said the US was working on an import ban, asset freeze and a ban on remittances to Myanmar.
"We continue our coordination with ASEAN countries and others who share our deep concern about the situation in Myanmar," Armitage said after a meeting in Washington on Friday with United Nations Special Envoy for Myanmar, Razali Ismail.
"We will continue to support democratic change in Myanmar through all available channels," he added.
Ismail brokered landmark secret talks between the junta and the National League for Democracy (NLD) in October 2000 aimed at shifting the country to democracy. They have now collapsed.
NLD leader Aung San Suu Kyi was placed under "protective custody" in late May, following attacks on her convoy by a junta-backed mob during a political tour in northern Myanmar that, according to eyewitnesses, left dozens dead.
Since then, NLD offices nationwide have been forcibly shut down and the senior NLD leadership in Yangon has been placed under house arrest.
Although the junta said it was a temporary measure, it has given no indication when Aung San Suu Kyi might be released, despite widespread international calls for her freedom.
After a spell at Yangon's notoriously tough Insein prison, she is now being held at an undisclosed location.
Her NLD party won the national elections in 1990 by a landslide, but has never been permitted to rule.