Natalie, 40, and Benjamin, 44, enjoyed a leisurely boat ride in Sydney with their pal Sacha, 49, and kids earlier this week but locals were outraged as residents have been ordered to stay home except for "essential' reasons" due to an outbreak of the highly infectious Delta variant of COVID-19.
The group were investigated by police but no breach was found.
NSW police said in a statement, "Officers attached to Northern Beaches Police Area Command received information about a group on a boat on Monday 5 July 2021, potentially breaching Public Health Orders (PHOs)."
"Police have reviewed the information and confirm the activity, and the number of people in the group, complied with the PHOs in force at that time. There will be no further police action taken."
The investigation came after a number of local residents took to Twitter to share their outrage, with Australian BBC correspondent Frances Mao tweeting, "So nice that Hollywood celebs get to enjoy Sydney Harbour during lockdown. Had no idea Natalie Portman and Sacha Baron Cohen were from one household..."
Meanwhile, police deploy 100 more officers to south-west Sydney to ensure compliance with rules."
Journalist Ben Grubb added, "What lockdown? Recreational activities are allowed as part of the sixteen rules but two separate families on a boat?"