Big family Christmas celebrations could be in jeopardy if Covid cases continue to rise during a "very challenging period" in the months ahead.
Scotland's Deputy First Minister was unable to say how long the new ban on gatherings between more than two households.
Concerns about a possible long haul through winter were raised with the senior SNP politician one day after Nicola Sturgeon confirmed a ban on more than six people from up to two households meeting socially inside or outside.
Asked on BBC Radio Scotland if big family Christmas celebrations are "cancelled", Swinney said: "Obviously, it's a while away but we've got to see how much progress we make before then."
Swinney added: "I think undoubtedly we face a very challenging period. We are only in September, we're seeing a rise in cases, we don’t know exactly how the virus will have an effect during the course of the winter.
"We have to act pro-actively at this stage to try to tackle what is a worrying increase in the prevalence of the virus. I think the public, I hope, will understand why we've acted at such an early stage to try to make sure we reduced the significance of the virus."
Swinney said Scotland is in a relatively strong position compared with the rapid spread in March.
The new rules come into force from Monday but the Scottish Government hopes people will follow the guidance immediately.
The social restrictions cover homes, public spaces, and hospitality premises such as pubs.
The total number of people doesn't include any children under the age of 12. That means you can take young kids round to a friend's house without worrying about breaking the limit.
The local lockdown restrictions in the Greater Glasgow area also remain in force for at least one more week.
Face coverings are also being mandatory when moving around pubs and restaurants.
Other plans to lift restrictions on sports stadiums and live entertainment are being pushed back from September 14 to October 5.
A review on call centres and offices opening up will not take place before October.
