France, Germany, Italy, and Spain have agreed to push for a 130 billion-euro ($163 billion) growth package at a key European Union summit next week.
Italian Prime Minister Mario Monti said after a four-way summit in Rome that the four countries admitted steps taken so far had not been enough.
He said both financial markets and EU citizens need to view the euro as irreversible, saying, "The euro is here to stay, and we all mean it."
German Chancellor Angela Merkel said eurozone leaders would work together on what she called "a political union" to solve the economic crisis.
Merkel added that "the lesson from the crisis is not less Europe, but more Europe."
French President Francois Hollande said the leaders had agreed on the need for a financial-transaction tax.
The Rome meeting comes ahead of a European Union summit on the financial crisis on June 28-29.
On the eve of the Rome talks, the head of the International Monetary Fund, Christine Lagarde, urged leaders of the 17 countries that use the euro to consider jointly issuing debt, aiding troubled banks directly, and perhaps relaxing strict austerity conditions on countries that have received aid.
Meanwhile, independent auditors say indebted Spanish banks may need up to 62 billion euros ($78 billion) in extra capital.
Based on reporting by Reuters, dpa, and AP