I understand that we need to follow the rule but I am quite curious as this only happens to my solvent (Acetonitrile). Do I need to dilute the solvent? How to overcome this problem? Thanks in advance.
There is no law which says that absorbance should be less than 1.0, its just a standard accepted range. The true range depends on the spectrometer.
I am also bit of confused by what do you mean by "solvent cut off peak of UV-Vis is above 1.0". Solvent cut-off means the transparency of the particular solvent is up to certain wavelength. In case of acetonitrile it is below 200 nm (http://macro.lsu.edu/HowTo/solvents/UV%20Cutoff.htm).
"Do I need to dilute the solvent?"
If you suspect that your spectrometer is small linearity range then you should dilute it. If instrument is not linear at higher absorbance value, then the absorption peak will become progressive flatter. If you cannot dilute it choose a cuvette with smaller path length and thereby decreasing the absorbance.
Again not sure what you mean by "this only happens to my solvent (Acetonitrile)". We measure solute (dye) not solvent.
If you are willing the share the data we might understand your problem better.