"There is broad and strong unity within the G7 on increasing sanctions and costs in response to escalating action from Russia," Lew said at a news conference, referring to the Group of Seven industrial nations, Reuters reported.
The G7 includes the United States, Canada, France, Germany, Italy, Japan and Great Britain. Top officials from the group met in Washington and discussed the situation in Ukraine at length, Lew said.
"In a discussion that went on for quite a long time in the room, there was no dissent in the room that it was essential that there be unity in taking action if necessary," he said.
Finance ministers and central bankers from around the world are in Washington for the spring meetings of the International Monetary Fund, Reuters reported.
The United States and Europe have enacted sanctions against Russia in response to Moscow's annexation of Crimea, which until recently was part of Ukraine.