Uganda's invasion of Tanzania last November has had a heavy impact on the fragile Tanazanian economy, even forcing the government to curtail some of its development plans for this year.

Talk in the local press of a "protracted war" aimed at overthrowing Uganda's mercurial president, Idi Amin, in revenge for the invasion has now ceased, and Tanzania seems anxious to find a way out of a situation that has required a continuing mobilization of its resources and energies to bolster its defense.

While the country remains on a war footing, there is little evidence of it other than a stream of irate letters to the editor and a butter shorage here in the capital. Tourists have continued to pour into the country to visit Tanzania's renowned game parks in the northeast and there is nothing in the hot, sultry air of Dar es salaam to suggest all is not right in the country.

[Radio Uganda charged Monday that Tanzanian forces had bombarded Uganda across the border near Lake Victoria. Ugandan President Idi Amin was quoted as warning that his forces moght retaliate.]

In a recent interview, President Julius Nyerere said the effort to repulse the invading Ugandans had required a "tremendous" diversion of Tanzania's meager economic means away from development projects and estimated the cost to the country might be running as high as $1 million a day.

This was the first time he or any other Tanzanian official had given an estimate of the financial and economic impact of the war on the agriculturally based economy.

He expressed fears that the worst effect might be to interrupt the new momentum in the economy's growth following a devastating drought in 1974-75. The bank of Tanzania has just announced that the economy grew by 6 percent in real terms last year, buoyed by an excellent harvest of food grains and increased industrial rpoduction.

The war also has proven a bitter political experience for the Tanzanian leader because a number of African leaders made appeals to him to settle the issue "peacefully" even though it was Uganda that invaded and seized Tanzanian territory.

Not only did Tanzania's Eastern Bloc friends, notably the Soviet Union, fail to condemn the Ugandan aggression but even the Organization of African Unity remained silent, despite Uganda's clear violation of the OAU's principles that all African states respect existing boundaries.

The two-week war ended in mid-november but there is still a state of tension along the border and both sides are keeping large forces mobilized there. The Tanzanians are convinced that Amin will try again to seize the Kagera salient, the 700-square mile area in northwest Tanzania his army seized in late October.

Nyerere said his efforts to get Amin to publicly renounce his claims to the region and pay compensation for the damages inflicted on Tanzania so far had been in vain.

Before Ugandan troops were driven out, they looted stores and homes, destroyed most buildings, including a sugar mill and churches, seized cattle and killed hundreds of civilians. The entire population in the salient, about 48,000 people, is being resettled south of the Kagera River on the assumption that fighting may resume again.

Nobody seems to know for certain why Amin sent his troops across to seize the salient when he did, but the prevailing theory here is that it was the result of a rebellion in one of his army's barracks and that loyal troops chased some of the fleeing dissidents across the border into Tanzania.

Whatever the cause, the invasion forced Tanzania to mobilize perhaps as many as 25,000 troops, buy heavy arms abroad, divert funds from other ministers and commandeer scores of trucks normally used to transport produce and export crops.

Ministries other than defense have been ordered to halt all new projects not under way already, not to fill vacancies, and cut back spending sharply on fixed costs, although the Tanzanians would not confirm this last point.

Even before the war started, the government was planning to tighten up on spending and end the more liberal imports policy initiated early last year because of rapid reduction in its hard currency holdings.These are said to have dropped since the beginning of 1978 from enough to cover six months of imports to barely one month now, or between $50 million and $60 million.

Increased imports of essential raw materials and spare parts for machinery contributed to the spurt in economic growth last year. Now there is talk of a 15 percent cutback in all imports, a measure likely to reduce industrial production this year.

The squeeze on the Tanzanian economy has led the government to open talks with the International Monetary Fund for a $125 million to $150 million loan. Tanzania, despite its poverty, has an excellent credit rating with foreign banks.

In any case, between the unexpectedly high cost of the war and the cramp in economic activity already under way, Tanzania seems destined to experience another tough year and possibly a setback in its ambitious development plans.