Though this has been answered, I would like to add my opinions on this.
Negations are always complicated especially when we have the following conditions:
We do not have the entirety of scriptures (puranas / vedas etc) that have ever been written available to us.
The scriptures are not a daily dairy of what every noteworthy person does in his/her lifetimes until death.
Hence I think we should mention something along the lines of:
There is no scriptural evidence (currently available) that point to the fact that Ravana met Parasurama. Hence it is unknown if they met. Or if they did meet, the meeting was not deemed noteworthy enough to be documented.
That would be the more accurate representation rather than negating the occurrence. Note that Ravana's and Parasurama's lifetimes overlapped, and they were among the illustrious ones of their times, they both worshipped Shiva and obtained weapons from him, and they lived / are living very long lives. It's quite probable that they would have met each other in some public gathering / one-on-one etc.