He said in a speech in the Verkhovna Rada on its first session day Thursday, Censor.NET reports citing Ukrainska Pravda.
Poroshenko emphasized he was the president of the whole country and of all Ukrainians.
He also said that there are still many people who wish Ukraine entered Eurasian economic customs union and support the idea of Russian language as the second national language.
"We would not allow such people the right to veto geopolitical decisions," the president said.
At the same time he assured that the idea of decentralization would allow to significantly consider local specifics, including in matters of religion and language.
At the same time Poroshenko promised to support Ukrainian language as the single national language.
"This doesn't take the issue of support of Ukrainian language off the agenda. What is called a positive discrimination in European political culture, is in fact a form of support of those who have been persecuted and victimized for it. Ukrainian language as the single national language is a very important henotic factor for the society and the state," the president said.
Poroshenko also indicated that Ukrainian people tend to support NATO accession much more now due to the activities by Russia. Although, the president said, this matter still divides the country.
Petro Poroshenko also warned that no federalization in possible in Ukraine.
"No federalization. This is a response to those who advise Ukraine to federalize, both from the East and the West," the president said and noted that most of Ukrainians do not support federalization as solution of the military conflict in Ukraine.
"Ukraine hasn't been as united before. Ukrainian political nation has footed itself in all the regions and united speakers of different languages," the President said.
As reported earlier, Russia insists on the federalization of Ukraine.