The United States' Melbourne-based consulate is among a number of foreign diplomatic headquarters across the city and in Canberra targeted with suspicious packages.
The deliveries on Wednesday sparked an emergency "hazardous material" response and in some cases, evacuation.
"We handled the package according to our standard procedures and in close co-ordination, with local authorities ... who are investigating the incident," a US spokesman said.
Manuela Erb, the honorary consul of the Consulate of Switzerland at Ashwood, told AAP they also received a suspicious package.
"It was in an envelope," she said.
Specialist firefighters were seen carrying large bags emblazoned with DANGER ASBESTOS as they exited the Indian and Korean consulates on St Kilda Road.
Both Pakistan and New Zealand's offices received envelopes containing small plastic bags with what appeared to be concrete and asbestos inside, ABC news reports.
Victoria Police confirmed a number of consulates in Melbourne received suspicious packages in what it said was a targeted attack.
"At this time we believe the matter is targeted and not impacting the general community," a statement read.
The Vic Emergency website showed firefighters responding to more than 10 "hazardous material" events occurring across Melbourne, which began unfolding about 1pm.
The New Zealand Ministry of Foreign Affairs and Trade told AAP staff at its William Street consulate were evacuated.
"The New Zealand Consulate General in Melbourne received a suspicious parcel this afternoon. Staff were evacuated from the consulate as a precautionary measure," a spokeswoman said.
Two fire trucks, a hazardous materials vehicle and police cars attended the Consulate-General of India where staff were also cleared from the building.
They were allowed to re-enter by 3pm when the area was deemed safe.
Ambulance Victoria confirmed a number of patients were examined at multiple consulates.
"No patients have required treatment or transport to hospital," it said in a statement.
The Australian Federal Police, who are overseeing the incident, would not say how many diplomatic offices were targeted.
"The packages are being examined by attending emergency services," they said in a statement.
"The circumstances surrounding these incidents are being investigated."
It is not known which embassies in Canberra have been affected, although AAP understands a hazmat team was performing an unrelated training activity at the US embassy.
The alerts come after Sydney's Argentinian consulate was partially evacuated on Monday following reports of a suspicious substance.
The powder, similarly contained in clear plastic bags within an envelope, was deemed not dangerous.