The truce agreement comes into force starting 6 pm local time (15:00 GMT).
The president has ordered to cease fire starting at the time stated in the protocol.
“I give the order to the chief of the General staff of the Ukrainian Armed Forces to cease fire, starting from 18.00 [local time] on September 5,” Poroshenko's statement says.
Poroshenko then called on both the Ukrainian Foreign Ministry and the OSCE to provide international monitoring of compliance with the bilateral ceasefire.
“We must do everything possible and impossible to stop bloodshed and put an end to people’s suffering,” the president said in a statement posted on his official website.
Both Donetsk and Lugansk have said they are ready to lay down arms starting from 15:00GMT.
Representatives of the rebel forces have said they will obey the ceasefire if Kiev follows suit.
“Most of the points of the protocol correspond with our demands,” Lugansk’s leader Igor Plotnitsky said.
“However, the ceasefire does not mean a shift from our course of breaking away from Ukraine. This is a compulsory measure,” he said.
The OSCE’s Heidi Tagliavini has welcomed the agreement saying “it is good news.”
She has revealed that the protocol consists of 12 points, and “the ceasefire is the chief one.”
The participants in the talks will prepare another document - a memorandum on settling the situation in Ukraine, a Donetsk representative said.
The two sides accompanied by representatives of Russia and the OSCE were meeting in the Belorussian capital, Minsk, in an attempt to end the bloodshed in eastern Ukraine.
Keep an eye on the US and the neo nazi freaks in Ukraine- I suspect very much the Nazi brigades have other loyalties, and the Azov battalion is quite active at this time
Ukraine crisis: the neo-Nazi brigade fighting pro-Russian separatists
Kiev throws paramilitaries – some openly neo-Nazi - into the front of the battle with rebels
The Azov battalion has the most chilling reputation of all. Last week, it came to the fore as it mounted a bold attack on the rebel redoubt of Donetsk, striking deep into the suburbs of a city under siege.The Azov men use the neo-Nazi Wolfsangel (Wolf’s Hook) symbol on their banner and members of the battalion are openly white supremacists, or anti-Semites.
The Azov battalion uses the neo-Nazi Wolfsangel (Wolf''s Hook) symbol on its banner (Tom Parfitt)
Azov’s extremist profile and slick English–language pages on social media have even attracted foreign fighters. ( Does that sound the least bit familiar? Recruiting foreigners? Think ISIS, which is being promoted as a 'world menace because of it's world wide recruitment/attraction. Why is Azov good? And ISIS bad? ) Mr Biletsky says he has men from Ireland, Italy, Greece and Scandinavia. At the base in Urzuf, Mikael Skillt, 37, a former sniper with the Swedish Army and National Guard, leads and trains a reconnaissance unit.