Adobe Illustrator to PDF export problem

Hi everyone,

I made a design and I prepared the Illustrator document for printing. 
When ready, I exported to PDF. But I noticed weird white lines on my design on the PDF version (see the design in attachment).
I tried to export again but the problem remains. 

What can I do to solve this ? 

Many thanks in advance for the help ! 

Kind regards, 

Morine