The Deputy First Minister told MSPs on Friday that Scottish Government analysis of traffic and transport data made it clear that too many people were still out and about – despite a “stay at home” order.
Ministers have already hinted that takeaway food and drink, click and collect services, manufacturing and construction could all face fresh legal restrictions amid concerns about activity levels, after a fresh national lockdown was ordered this week.
Labour MSP Monica Lennon suggested more Scots appeared to be "out and about" than during the first lockdown in spring last year during meeting of Holyrood’s Covid-19 committee on Friday.
Mr Swinney told MSPs that it is now a "requirement in law" for people and organisations to follow the “stay at home” rules which have been issued by ministers.
"We are monitoring very closely the levels of interaction in society," Mr Swinney said.
"We're monitoring very closely public transport use, we're monitoring closely traffic data, we're monitoring closely all of the information that's available to us around the level of movement in society.
"I think Monica Lennon is probably correct in that the volumes of movement in society are greater than they were in the period immediately following lockdown in March of 2020.
"We are monitoring those issues very carefully with a view to potentially having to put in further measures that would further constrain the ability of individuals to have reasonable excuse to be at work, for example, and for employers to essentially justify those being at work."
The Deputy First Minister said industries like construction had done a "great deal of work" to make its operations safe.
But he said: "There is still too much movement in society and we do not see a reduction in the level of infectiousness."
And Mr Swinney warned: "We may have to take further action as a consequence … to apply greater restrictions if we don't see a fall in the level of infection."