Tajani told the German Funke Media group that the date of Brexit can be delayed past March 29 by only a few weeks at most.
"It's a matter now of avoiding the biggest mistake of all — a chaotic Brexit without contractual arrangements in place," Tajani said in an interview due to be published on Saturday.
He suggested that a disorderly no-deal Brexit would be a disaster for the British economy and would also hurt the EU, adding that he would be happy if the UK would choose to remain in the Union.
Tajani said the political declaration on Brexit could perhaps be slightly more clearly formulated but he ruled out changing the withdrawal agreement, especially on the so-called “backstop” with Northern Ireland – the most controversial part of the agreement with UK Prime Minister Theresa May.
"I'm convinced that the exit date can only be delayed by a maximum of several weeks — from the end of March to the start of July at most," he said.
"They've decided to leave — it's their problem, not ours," he added.
He also suggested that Britain's exit from the EU would deter other countries from leaving the bloc, saying that the Union needs a change, “but we need to stick together.”
The British Parliament is set to vote on May's Brexit plan for a second time on Tuesday. The UK PM said that if her plan is defeated, lawmakers will be able to vote on Wednesday and Thursday on whether they want to leave the bloc without a deal, or ask the EU for an extension of article 50.