The Pakistani opposition today rejected a new offer of talks by Prime Minister Zulfiqar Ali Bhutto and for the first time described the bloody mass agitation against his rule as a Jihad, a Moslem holy war.

The nine-party Pakistan National Alliance, in its strongest statement yet, said Bhutto has usurped power. It again demanded that he resign. The opposition leaders pledged to continue leading their supporters in their "Jihad" against him.

This is a volatile notion in fervently Moslem Pakistan, where at least 170 persons are reported to have died in street violence since the opposition began its campaign against Bhutto six weeks ago, charging that he rigged the March 7 national elections.

Bhutto refused to resign yesterday but he renewed an offer to talk and he banned liquor, gambling and nightclubs in a concession to those orthodox Moslem feelings to which his opponents have often appealed.

Clashes between opposition demonstrators and young members of Bhutto's Pakistan Peoples Party continued today with three deaths reported in Lyallpur, 90 miles south of Lahore.

Previous clashes mostly have involved demonstrators and police or paramilitary forces and the recent movement of the Peoples Party into the fray increases the chances of violent confrontation.

In Lahore, acting National Alliance chief Nawabzada Nasrullas Khan told a crowd of 20,000 that Bhutto wants "to push the county toward civil war so that we can continue in office."

While the demonstration in Lahore was largely peaceful, some of the marchers carried firearms and police dispersed part of the crowd that broke away and burned down a bookstore belonging to a Bhutto supporter.

Today's demonstration was one of the largest in Lahore since the campaign against Bhutto began. Lahore is the capital of the critical Punjab Province, the key to national power.

The opposition agitation has now broadened to include attempts to paralyze the railways and road transport by mass travel without tickets. Campaigns to withhold taxes and withdraw bank deposits have been under way for some time.