Twelve people died in Berlin on Monday evening after a lorry drove straight into a Christmas market. But the attack does not mean a higher threat level against Sweden, according to the security and intelligence service Säpo.
In an interview with Swedish Radio, Wallström said that the government is as ready as possible to deal with a threat.
"We have had a strategy against terrorism for the last year and a half and are working very actively with everything that may be a threat, and to ensure that we are as prepared as we can be," she said.
She called it a "terrible attack that bears all the hallmarks of terrorism" and says it is understandable that people are afraid.
"We have to be able to think that this may be something that could affect us here too, and the government is prepared and we have exercises and other things that means we would hopefully be able to deal with a situation that may occur," she said.
Wallström was in touch with her German counterpart Frank-Walter Steinmaier on Tuesday morning to offer her condolences and support if needed.
She has also spoken to the Russian ambassador to Sweden and offered her condolences, after the Russian ambassador to Turkey was gunned down and killed at a gallery in Ankara on Monday evening. She praised Turkey and Russia for acting quickly to try to calm the situation after the incident.