Can I plug a 13A washer machine into a 20A power source?
The markings on the terminal block should indicate the rating of the terminal block, not the electrical consuption of the appliance.

Also, washers usually do not consume more than 1,000 watts or so; at 120Vac things would be fine given about 8-9 amps current draw @ 1,000 watts.  At 240Vac, you should be golden with a current draw of 4-5 amps.

I say wash away without worry.  Could be wrong though I guess.