MUNICH—European officials brushed off U.S. Vice President Mike Pence’s calls during a diplomatic trip to the continent this week to ratchet up pressure on Iran, saying they will continue defending the 2015 nuclear deal and stay engaged with Iran’s government.

At the annual Munich Security Conference over the weekend, where world leaders gather to debate issues from the Middle East to trade, senior European officials met with Iranian Foreign Minister Javad Zarif. Mr. Zarif on Sunday blasted what he called Mr. Pence’s arrogant...