"We reiterate our rejection of the USA decision on Jerusalem", said the king, adding that "East Jerusalem is an integral part of the Palestinian territories".
Sixteen Arab leaders are attending the summit, which comes one day after the U.S., France and Britain launched a joint airstrike in Syria in the wake of a suspected chemical attack by regime forces.
Saudi King Salman bin Abdulaziz Al Saud referred to the Palestinian issue as the top agenda of the Arab meeting.
"East Jerusalem is an integral part of the Palestinian territories", he added.
"We renew our strong condemnation of Iran's terrorist acts in the Arab region and reject its blatant interference in the affairs of Arab countries", the king said.
AL Secretary General Ahmed Aboul-Gheit noted that the crises gripping the Middle East will further deteriorate and weaken the entire region if not harnessed.
US President Donald Trump's decision to transfer his country's embassy to occupied Jerusalem was a top concern for Jordan, which has tirelessly worked, making intense contacts at all levels and garnering wide global support for its stand in opposing the US move and supporting the Palestinians' right to set up their independent state.
He believed there has been a huge setback in the process of solving the Palestinian-Israeli conflict after U.S. President Donald Trump's announcement.
President Mahmoud Abbas, along with a number of Palestinian senior officials, arrived at King Abdulaziz Air Base in Dhahran city, Saudi Arabia, on Saturday to participate in the summit.
An Arab League summit started in Dhahran, Saudi Arabia today (Sunday).