Everton confirmed on Friday that Jagielka is likely to miss around six weeks after suffering a knee injury and, with only Sylvain Distin and John Heitinga now available in that position, Moyes has signalled his intent to enter the transfer market.
"We are down to two centre-halves so it is going to make it difficult to cope for that time with two central defenders," he said. "We know we don't have great finances so we know it will be a problem to do that.
"We'd like to add to one or two positions and, with the injury to Jagielka, it leaves us short at centre-half. We are looking to try to do something but it will more than likely be in the loan market - but if we see anything out there that we think is right for us we will obviously try to get it.
"It is never an easy time to get players in but we will try."