"It is obviously very positive that this meeting can be held... but at the same time I think we need to be cautious," Parly said while attending the Eurosatory arms exhibition.
She said she was being "very pragmatic" while awaiting the results of the historic talks, "without being naive or thinking that things can change in a day just like magic."
"It's a process which is just beginning and we will judge any progress step by step," Parly added.
Trump and Kim are scheduled to hold historic face-to-face talks in Singapore on Tuesday, a meeting that would have seemed unimaginable just a few months ago as tensions flared between the two leaders over the North's missile and nuclear programmes.
Trump would be the first sitting US president to negotiate directly with a member of the Kim dynasty.
But analysts say it is unclear if Pyongyang will agree to "complete, verifiable and irreversible" denuclearisation, as demanded by the United States.