It's hard to disprove a claim, especially one without much background information. I am unaware of such a claim. While Jews being allowed to lend at interest more than Christians was "a thing" that affected Jewish society, being Jewish generally came with pretty serious social/economic restrictions that would outweigh being allowed to lend money at interest. And in many Christian societies conversion to Judaism would not be allowed at all.

It's difficult to say more than that, really, without a specific claim. The time period also needs clarification--by phrasing it "Romans" it sounds like late Roman empire, but people generally associate Jews being the people lending money with Northern Europe during the Latish Middle Ages.