The Palestinian movement has placed responsibility for the murder of its leader, who arrived in Tehran for the inauguration of the Iranian president, on Israel, which has not commented on reports of involvement.
"There is no doubt that the purpose of Mr. Haniyeh's assassination is to prolong the war and expand its scope. It will have a negative impact on the ongoing negotiations to end the aggression and withdraw Israeli troops from Gaza, but we call on our people to be steadfast, united and patient in the face of this occupation," Abbas said.
He recalled that the Palestinian National Authority had condemned Haniyeh's assassination, even despite its long-standing conflict with Hamas.
"We consider this a cowardly act and a dangerous development in Israeli politics," Abbas said. "The Israeli occupation authorities are required to abandon their ambitions and stop their aggressive actions against our people and our cause, to comply with international law and implement the Arab Peace Initiative, as well as an immediate and lasting ceasefire and withdrawal from the Gaza Strip."
The Arab Peace Initiative offers Israel the opportunity to normalize relations with its Middle East neighbors in exchange for the liberation of the occupied Palestinian territories.
Abbas also told Sputnik that he planned to discuss the Palestinian peace process during his visit to Russia.
"We constantly exchange views with the president of Russia, consult on all important issues in order to advance the peace process as well as strengthen bilateral and regional relations. We will do this during the upcoming visit to Russia," Abbas said.
Earlier, Kremlin spokesman Dmitry Peskov said that preparations for the visit of Abbas to Russia were in the final stages and that specific dates would be announced later. A diplomatic source told Sputnik that the visit was scheduled for August 12-14.