The roadie will probably be faster. The mountain bike will not even be a mountain bike.
At your price range:
- Tyre rolling resistance, both bikes will probably have crappy tyres, it is likely, but not certain, that the road bike will have less rolling resistance.
- Weight of the bike, the MTB will be at least 3 kilos heavier, this is a plus on descents, irrelevant on flats, bad on ascents. Rotating weight will hinder acceleration.
- Aerodynamics, the faster you go the more important this is, that road bike appears to be reasonably aerodynamic and will put you in a more aerodynamic position than most mountain bikes.
- Wheel size, the 26inch wheels roll worse on everything, even if you get the mountain bike, try to avoid 26inch wheels for your purposes.
Damaging the wheels from cobbles and cracked pavement is not very likely, however it is not so uncommon for new wheels to need to be trued again after bedding in over 300km or so. I know several people who ride 28mm in Moscow on cheap road bikes, lots of nasty roads there, only ever heard complaints about sore buttocks, not broken wheels.
Please note that "higher pressure = less rolling resistance" is a simplistic generalisation which, despite having general truth to it, is ultimately false for road bikes and a very flawed way of thinking for mountain bikes on actual mountain bike terrain.
Depending on their construction the 32mm tryres might be FASTER than your 25mm, or if you have hard rubber with puncture resistant layers etc then both the 32 and 25mm could conceivably roll worse than tubeless 2.25inch Racing Ralph evo MTB tyres being run at 35psi, let alone an expensive MTB semi slick run at a high pressure: http://www.bicyclerollingresistance.com/mtb-reviews/continental-speed-king-ii-racesport-2015
Take a look at the comparison of these 32 to 47mm tyres to see something rather unexpected also: http://www.bicyclerollingresistance.com/specials/schwalbe-marathon-32-37-40-47
The take away lesson should be that most people cannot tell much about rolling resistance without actually measuring it, in an appropriate setting, furthermore, most simplistic assumptions about rolling resistance are likely to be invalid in the real world (elements of these measured tests included) as has been repeatedly shown in recent years.
P.S. I would never recommend an urban bike to anyone ever, I would also never recommend a mountain bike under around 700euros (buy second hand if you can't afford 700euros!) as it simply will not be an actual mountain bike, even 700euros is really border line for an actual mountain bike, but there are some appearing at that price range, you just have to wade through all the trash to find them.