The offences took place between October 2020 and December 2021.
Ojiri founded Ramp Gallery, now known as the Ojiri Gallery, based in east London.
Mr Harris said: "There is one discussion where Ojiri is party to a conversation where it is apparent a lot of people have known for years about [Ahmad's] terrorism links."
He added that "Ramp Gallery engaged a third party to advise on compliance matters" but that the advice given was "not properly acted on".
Westminster Magistrates' Court heard that Ojiri "dealt with Mr Ahmad directly, negotiated the sales of artwork and congratulated him on purchases".
The prosecution's case claimed that at the time of the transactions, there was a significant amount of online material showing Ahmad's alleged links to the "blood diamond" trade - a reference to how diamonds are sometimes used to fund armed conflict and insurgencies.
