Poroshenko's remark came on Sunday, a day after German Chancellor Angela Merkel and Russian President Vladimir Putin discussed the possibility of four-way talks between Ukraine, Russia, France, and Germany at the G20 summit in Argentina.
The four countries form the ‘Normandy Four’, which was set up to resolve the conflict in eastern Ukraine involving Russian-backed rebels.
Poroshenko told the French broadcaster, France 24, that Merkel agreed to the proposal in his talks with the German leader.
“We will certainly take part in the meeting of the Normandy format at the level of political advisers, where we will raise the urgent question: the requirement for the Russian Federation to return our military, ships and open the Kerch Strait,” he said.
“We demand [from Russia]: stop violating international laws ... [it] may have further consequences,” Poroshenko said.
He also said that Moscow “should withdraw its troops stationed on the Russian-Ukrainian border and remove a large number of warships from the Sea of Azov.”
Ukraine has also called on Germany and its allies to boost their naval presence in the Black Sea to deter Russia from further aggression in the region.
'Russia has been rejecting talks'
Volodymyr Fesenko, director of the Penta Centre for Political Studies in Kiev, told Al Jazeera that Ukraine has always been in favor of negotiation.
“Russia is the one that has been rejecting it. Poroshenko tried to talk to him right after the incident in the Kerch Strait, Putin rejected it. Then, the foreign ministers of the Normandy format met in Berlin, but we are told the Russian side refused to discuss the Kerch situation,” he said.
“Now, it is clear why. Russia is blocking the talks since it is waiting for the end of the (March 31) presidential elections in Ukraine.”
He also said that without the Normandy format talks, there would be no Minsk Agreement “and at least partial implementation of those accords.”
“All serious questions have been resolved in the Normandy format only. Without mediators like Germany, there would have been no progress,” he said.
Oleksiy Haran, head of research at Ilko Kucheriv Democratic Initiatives Foundation, told Al Jazeera that Ukraine is unlikely to go for talks with Russia without a third party.
“Whenever we have bilateral talks, Russia violates it. There is no trust with Russia,” Haran said.
The rift between Russia and Ukraine intensified after Kiev ousted the Moscow-backed president, Viktor Yanukovich, in 2014.
It turned into a conflict following the Russian annexation of Ukraine's Crimean Peninsula and the seizure of Donetsk and Luhansk regions in the east by Russia-backed rebels the same year.
The conflict between the two neighbor states reached a new low last Sunday after the Russian border patrol blocked three Ukrainian military vessels from traveling from the Black Sea to the Sea of Azov through the Kerch Strait - the shared internal waters of both states according to a 2003 agreement.
On Saturday, Poroshenko, who believes Moscow wants to conquer the whole of Ukraine, said there were more than 80,000 Russian soldiers in and around his country
The Kremlin has accused the Ukrainian president of playing up the conflict with Moscow to secure electoral support in the upcoming presidential election.