Finland and Sweden sought NATO membership shortly after Russia's invasion of Ukraine last year, and while most member states have ratified the applications, Turkey has yet to give its approval in what must be a unanimous process.
The three nations last year reached an agreement on a way forward, but Ankara suspended talks last month as tensions rose following protests in Stockholm, where a far-right politician burned a copy of the Muslim holy book, the Koran.
"The first thing we need to do is calm down the situation. It is hard to have good talks when things are literally burning around you," Kristersson told a news conference during a visit to Estonia's capital.
He said preconditions for restarting talks were good, but that with Turkish elections due in May, it was understandable Turkey was focused on domestic policy.
"As soon as they are prepared (for talks), we are obviously prepared," Kristersson said.
Turkey last week said it looks positively on Finland's application, but does not support Sweden's, even though the two Nordic neighbours are seeking to join at the same time.
Finnish President Sauli Niinisto on Tuesday said he hoped Finland and Sweden would soon become members.
"The goal is to be accepted as soon as possible, both Finland and Sweden," Niinisto told a joint news conference in Helsinki with Canada's visiting governor general.
Finland and Sweden are progressing in full "co-understanding" and remain in close contact with NATO's headquarters, the White House and Turkey, Niinisto said.
Estonia's Prime Minister Kaja Kallas said the wider Baltic area would benefit from Sweden and Finland becoming members.
"For the security of our region, it would be better if both countries joined," she said.
(Reporting by Simon Johnson and Terje Solsvik, editing by Anna Ringstrom and Ed Osmond)
