"I haven't been able to get permission to go into Gaza ... I asked for permission, but I was turned down," Carter said.
"But maybe we can find a way to circumvent that. I don't know yet."
All of the border crossings between Israel and Gaza are controlled by Israel and Egyptian forces are stationed at Gaza's southern border, which is largely closed.
The Israeli government has been critical of Carter's visit, mainly over his plans to meet Khaled Meshaal, Hamas's top leader, in Syria.
Carter said he would use his meeting with Meshaal to "get him to agree to a peaceful resolution of differences, both with the Israelis ... and also with Fatah".
"Since Syria and Hamas will have to be involved in the final peace agreement, they ought to be involved in the discussions leading up to ... peace," he said.
Despite heavy Israeli criticism since his arrival on Sunday, Carter met Naser al-Shaer, who served as deputy prime minister in the Hamas-led government, formed after it won parliamentary elections in 2006.
Later he placed a wreath at Arafat's mausoleum.
While many foreign dignitaries have done this in the past, George Bush, the US president, pointedly did not do so during his recent visit to Ramallah.
The Bush administration had shunned Arafat, accusing him of fomenting violence, an allegation he had denied.
Carter, who brokered Israel's first peace treaty with an Arab neighbour - Egypt - signed in 1979, has said he hoped to become a conduit between the armed Palestinian movement, Washington and Israel.
While he met Shimon Peres, Israel's president, in Israel on Sunday, he was shunned by Ehud Olmert, the prime minister, and other policymakers.