Hi all,
I have a Jetta 2013, Highline 2.0, Petrol.
When I start the engine in the morning, it starts shaking severely and the engine rpm goes up about 2000rpm. it continues for about 30 seconds and disappears after that and engine rpm will be back to about 1000rpm.
Also during it's shaking time, if I push gas pedal and make it go beyond 2000rpm, the shake will disappear as well, and when I release gas pedal, again the shaking will start till ending warm-up time.

VW dealer said that it's OK. but I'm not too sure about that. it's quite noticeable.

Sometimes even after one hour driving, it fairly vibrates, I mean it can work smoother but I assume that it might be because of the age of the car.
On the internet I found a bunch of potential causes such as battery, engine mounts, oil and air filter, spark plugs, spark plugs wires, etc.
The car is serviced regularly and battery is changed recently.
What do you think the most probable cause can be?