How much is "a bit bigger than allowed"?
Can you get past the limit by doing a bit of cropping, or do you need everything at the edges of the photo to be in the print?
What type of compression is the TIFF file using (if any)? If you're not using compression, then IIRC there are options for lossless compression in the TIFF format, depending on the specifics of what is in the picture.