In the hanafi fiqh markooh tahrimi seems to mean that something is not clearly considered as haram by a text (so there's a dispute among scholars, which leave a hint of a doubt about the unlawfulness of this act).
When we read verse in (5:5):
... And [lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you, when you have given them their due compensation, desiring chastity, not unlawful sexual intercourse or taking [secret] lovers ...
we must be aware that scholars have different opinions and interpretations of the part about the chaste women among people of the book:
Some say it is not lawful to marry christian or jewish slaves (among them Imam Malik, but this is based on a verse in surat an-Nisa')!
Others say it is only halal to marry free women among people of the book whom are not actually in war with Muslims (among them the hanafis). So marrying a dhimi lady (tribute paying non-Muslims who are protected by Muslims) would be lawful for all those scholars, while marrying a woman from a country which is at war with Muslims (dar al harb) wouldn't be for some of them.
So as you see there's a dispute here even if the Quran aparently says that it is lawful. I hope this helps for now.
For details on the hanafi madhab I'd recommend you to check tafsir abu Bakr al-Jassas ابو بكر أحمد بن علي الرازي الجصاص it is a tafsir al-ahkam.