Chief Executive John Lee said on Tuesday that officials will monitor whether a relaxation of rules for inbound travellers leads to a rebound in Covid cases.
He said society has largely welcomed the move to scrap hotel quarantine for arrivals and instead give people an amber health code to ban them from restaurants, bars and other venues for three days.
Lee described the change in rules as major and said it brings with it some uncertainties, including whether the health code arrangement will be complied with and whether people will get Covid tests as ordered.
He said rule-breakers should be condemned.
"If they don't do [the tests], the success of the 'zero plus three' plan will not be as effective because there may be a rebound of cases, simply because of people not complying with what they're required to do," the CE said ahead of this week's Executive Council meeting.
"We have to condemn this non-compliance because it affects everyone of us, it affects my plan of looking at possible new areas where we can allow more free activities."
Lee said as Hong Kong opens up, he expects different activities to resume including exhibitions and people arriving in the city on business trips.