Can I connect DC12v on VAC output (2A 100-240V) relay?
First be sure this relay is built with MOSFETs or SCRs. If built with triacs they will NOT work with DC. Worse case is you have to buy a compatable or conventional relay, else:

As long as you do NOT exceed the voltage or current rating of the output, it is a "Don't care" scenario. With an AC rating you could change polarity of the DC voltage and it would still be "Don't care".

Be aware that you maybe running the relay at its current limit, so if it gets hot put it on a large heatsink. Since it expects a much higher voltage it may have some internal resistance that will cause a voltage drop under full load. If less than a 1 volt drop I would just live with it. If the drop is several volts than you need a source greater than 12 volts to make up for the loss.