If the opposition says no, "we will go ahead anyway, then there will be a referendum," Tajani told Mezz'ora in più on Rai3.
"Majority and opposition: solutions must be found together," he added.
Opposition parties have been summoned to meet with Prime Minister Giorgia Meloni on Tuesday to begin discussions on proposed constitutional reforms to introduce a semi-presidential system similar to that applied in France.
Meloni made introducing such a reform by the end of this parliamentary term a central part of her campaign manifesto.
"For Italy, a presidential style of government could be a solution, I see it as going down better with political forces. I am pragmatic, I am interested in stability," Tajani explained.
"I think citizens have the right to choose their government," he added.
Earlier in the day centre-left Democratic Party (PD) whip Francesco Boccia said his party would "go and listen" to the proposals, but that "the debate will take place in parliament".
"For us the priority remains the economic and social emergency about which the government is not doing enough," he added.
Populist opposition party Five Star Movement (M5S) leader and ex-prime minister Giuseppe Conte took a similar line.
"We will listen but we will make it clear from the beginning that negotiations must grow out of a shared diagnosis. Then we will start discussing remedies," he said.
On Sunday the regions also asked to be included in the discussions.
ANSA
