"I gave my word that I would do nothing destructive to the constitutional initiative adopted by parliament, so none of Ukraine's 48 million citizens can say Yushchenko is defending his powers."
The president was referring to the constitutional changes approved late last year in a compromise move during the controversial presidential elections.
The changes are due to come into effect in January, ahead of the parliamentary elections in March.
The president also said he would try to patch relations with ambitious Ms Tymoshenko, but admitted that it "should be a different relationship", BBC reported.
"If all Yulia Volodymyrivna (Tymoshenko) seeks is power and power alone, it is her choice. I am no partner for her in this," he said.
Mr Yushchenko had earlier said his decision to fire the entire cabinet was forced upon him by the absence of unity and bitter infighting in his former government team.
Ms Tymoshenko blames aides to the president for the "deeply unjust" move and has distanced herself from Mr Yushchenko.
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