Do rules of trade only concern the Muslim community?

No, this is trade in general, because Islam does not make a distinction between dealing with Muslims and dealing with non-Muslims in terms of honesty. Honest is one of the intrinsic qualities of the believer.[1] He does not turn it off when he is dealing with non-Muslims and he does not turn it on when he is dealing with Muslims- this is one of the signs of the deviation of the Jews. We know in the Torah, in the Old Testament, that the Jews were prohibited in dealing with riba[2] so they changed the text to say, you are prohibited in taking riba amongst yourselves, but you may take it from the Non-Jews.[3]

References:

[1]“Allah does not forbid you to deal justly and kindly with those who fought not against you on account of religion and did not drive you out of your homes. Verily, Allah loves those who deal with equity.” [Surah Al-Mumtahinah, 60:8]

[2]Interest, Usury (Dr. S Al-Fawzan, A Summary of Islamic Jurisprudence, 35)

[3]Deuteronomy 23:20: “You may charge a foreigner interest, but not a fellow Israelite, so that the LORD your God may bless you in everything you put your hand to in the land you are entering to possess.”(New International Version)